Skip to content

multibinit input variables

This document lists and provides the description of the name (keywords) of the multibinit input variables to be used in the input file for the multibinit executable.

analyze_anh_pot

Mnemonics: ANALYZE ANHarmonic POTential
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials
  • 0 → Nothing.
  • 1 → Print energy contribution of each anharmonic term in the effective Potential. If it is a Molecular Dynamics (MD) run, the contribution of each term is printed for each MD-step into MD_anharmonic_terms_energy.dat . If the effective potential is tested against a test set the contribution of each term for each configuration in the test set is printed in TES_anharmonic_terms_energy.dat . If the effective potential is fitted, the contribution of each selected term for each configuration in the training set is printed in TRS_anharmonic_terms_energy.dat

bmass

Mnemonics: Barostat MASS
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: 10
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

See bmass

bound_anhastrain

Mnemonics: BOUND ANHArmonic STRAIN coefficients
Mentioned in topic(s): topic_BoundingProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Flag to activate the anharmonic strain. When the bound process will generate the possible coefficients for the fit, if this input variable is set to 1, the generator will consider coefficients like eta^4

bound_cell

Mnemonics: BOUND superCELL size for the molecular dynamics
Mentioned in topic(s): topic_BoundingProcess
Variable type: integer
Dimensions: (3)
Default value: 6,6,6
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

When the process will try a given model, this input variable is used to set the size of the supercell for the molecular dynamics

bound_cutoff

Mnemonics: BOUND CUT OFF
Mentioned in topic(s): topic_BoundingProcess
Variable type: real
Dimensions: scalar
Default value: 1 unit cell
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Cut-off for the anharmonic phonon interaction during the bound process (in Bohr)

bound_factors

Mnemonics: FACTORS for Goal Function of Energy, Forces, and Stresses during bounding process
Mentioned in topic(s): topic_FitProcess
Variable type: real
Dimensions: (3)
Default value: [1, 1, 1]
Added in version: v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify three factors for Energy, Forces and Stresses in the calculation of the Goal Function which is to be minimized during the bounding process, allowing to change the relative weights of the three quantities.

Default value is 1 1 1, equally balancing energy, forces and stresses.

bound_maxcoeff

Mnemonics: BOUND MAX COEFFicient
Mentioned in topic(s): topic_BoundingProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Number of maximum additional coefficients for the bound process

bound_model

Mnemonics: BOUND MODEL
Mentioned in topic(s): topic_BoundingProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [3/58] in all multibinit tests, [1/10] in multibinit tutorials

Flag to activate the bound process:

  • 0 → Do not activate the bound process

  • 1 → This option will generate all the possible combinations of coefficients from 1 to bound_maxcoeff. Some constrains are imposed during the generation and the fit of the coefficients, they have to be positive and with even power. Finaly, the code will try all the possible combinations and try to find a bounded model.

  • 2 → new version This option will generate a set of coefficients with a power range defined by bound_rangepower and keep only the coefficients with even power. Then the procedure is similar to the fit process with the constrains to only keep positive coefficients. The bound process will select the coefficients one by one up to bound_maxcoeff and try if the model is bound at each step of the process.

Related variables:1 and 2 The number of maximum additional coefficient in the polynome (bound_maxcoeff), the power range for the additional coefficients (bound_rangepower), the cut off of the additional interactions (bound_cutoff)

*3 → Check each anharmonic term in the effective potential. If the term contains has a negative coefficient and is even in its displacement or contains odd powers in the displacement generate high order bounding terms of the same combination of displacement within the range of powers defined by the user (bound_rangepower). The coefficients of the added high-order terms are optimized until the precision of the original effective potential is retained.

bound_penalty

Mnemonics: Goal Function penalty for determination of bounding coefficients
Mentioned in topic(s): topic_FitProcess
Variable type: real
Dimensions: scalar
Default value: 1.001
Added in version: v9

Test list (click to open). Moderately used, [2/58] in all multibinit tests, [1/10] in multibinit tutorials

Relative penalty for the determination of bounding coefficient values. The penalty defines the ration of the goal function before and after adding the coefficient. If the optimum value of the coefficient (-one that decreases the value of the goal function-) is negative a positive value that .

bound_rangepower

Mnemonics: BOUND RANGE POWER
Mentioned in topic(s): topic_BoundingProcess
Variable type: integer
Dimensions: (2)
Default value: 6,6
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Range of the power for the additional coefficients in the bound process

bound_spcoupling

Mnemonics: BOUND Strain Phonon COUPLING coefficients
Mentioned in topic(s): topic_BoundingProcess
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Flag to activate the strain phonon coupling. When the bound process will generate the possible coefficients for the fit, if this input variable is set to 1, the generator will consider coefficients like (Sr-Ti)^2 eta^2

bound_step

Mnemonics: BOUND number of STEP for the molecular dynamics
Mentioned in topic(s): topic_BoundingProcess
Variable type: integer
Dimensions: scalar
Default value: 1000
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

When the process will try a given model, this input variable is used to set the maximum number of molecular dynamics steps

bound_temp

Mnemonics: BOUND TEMPerature for the molecular dynamics (in Kelvin)
Mentioned in topic(s): topic_BoundingProcess
Variable type: integer
Dimensions: scalar
Default value: 500
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

When the process will try a given model, this input variable is used to set the temperature for the molecular dynamics

coefficients

Mnemonics: values of the COEFFICIENTS
Mentioned in topic(s): topic_LatticeModel
Variable type: real
Dimensions: (ncoeff)
Default value: 0.0
Added in version: before_v9

Test list (click to open). Moderately used, [19/58] in all multibinit tests, [1/10] in multibinit tutorials

Set the values of the coefficients present in the XML file

dipdip

Mnemonics: DIPole-DIPole interaction
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Very frequently used, [44/58] in all multibinit tests, [5/10] in multibinit tutorials
  • 0 → Do not recompute the dipole-dipole interaction.
  • 1 → Recompute the dipole-dipole interaction based on ewald summation .

dipdip_prt

Mnemonics: DIPole-DIPole PRinT
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Very frequently used, [36/58] in all multibinit tests, [0/10] in multibinit tutorials
  • 1 → Print the dipole-dipole interaction into the XML.
  • 0 → Do not print the dipole-dipole interaction into the XML.

dipdip_range

Mnemonics: Dipole-Dipole range
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: (3)
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Depending of the cases, the range of the dipole-dipole interaction will be parameted by:

  • dipdip_range if superior to ncell and superior to short-range interaction
  • ncell if dipdip_range inferior to ncell
  • short-range if dipdip_range inferior to short-range interaction

For example:

* if dipdip_range = 2 2 2 and the short range interaction if 3 3 3, the dipdip interaction will be set on 3 3 3

* if ncell = 15 15 15 and the dipdip_range is 6 6 6, the dipdip interaction will be set on 15 15 15

dtion

Mnemonics: Delta Time for IONs
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 100
Added in version: before_v9

Test list (click to open). Moderately used, [10/58] in all multibinit tests, [1/10] in multibinit tutorials

See dtion

dyn_chksym

Mnemonics: DYNamics CHeK SYMmetry
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Flag to activate symmetry finder and imposition of symmetry of the restart structure before dynamics run, when restartxf is negativ. Useful to do symmetry constrained relaxation with structural realxations algorithms. Be cautious to use it with large number of atoms, symmetry detection might take a long time.

Related variables: Restart flag for multibinit dynamcis (restartxf), symmetry on symmetry finder (dyn_tolsym))

dyn_tolsym

Mnemonics: DYNamics TOLerance on SYMmetries
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: 1e-10
Added in version: v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Tolerance on symmetry finder. Related variables: Activation flag for symmetry finder (dyn_chksym)

dynamics

Mnemonics: Dynamics option for Multibinit
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Very frequently used, [39/58] in all multibinit tests, [6/10] in multibinit tutorials

Set the Dynamics option for Multibinit. This option is equivalent to ionmov for numbers < 100. For numbers >100, it uses algorithms implemented inside Multibinit:

  • 0 → do nothing

  • 1 → Move atoms using molecular dynamics with optional viscous damping (friction linearly proportional to velocity). The viscous damping is controlled by the parameter “vis”. If actual undamped molecular dynamics is desired, set vis to 0. The implemented algorithm is the generalisation of the Numerov technique (6th order), but is NOT invariant upon time-reversal, so that the energy is not conserved. The value ionmov = 6 will usually be preferred, although the algorithm that is implemented is lower-order. The time step is governed by dtion. Purpose: Molecular dynamics (if vis = 0), Structural optimization (if vis >0) Cell optimization: No (Use optcell = 0 only) Related variables: Viscous parameter vis, time step dtion, index of atoms fixed iatfix

  • 2 → Conduct structural optimization using the Broyden-Fletcher-Goldfarb-Shanno minimization (BFGS). This is much more efficient for structural optimization than viscous damping, when there are less than about 10 degrees of freedom to optimize. Another version of the BFGS is available with ionmov==22, and is apparently more robust and efficient than ionmov==2. Purpose: Structural optimization Cell optimization: Yes (if optcell/=0) Related variables:

  • 6 → Molecular dynamics using the Verlet algorithm, see [Allen1987a] p 81]. The only related parameter is the time step (dtion). Purpose: Molecular dynamics Cell optimization: No (Use optcell = 0 only) Related variables: time step dtion, index of atoms fixed iatfix

  • 7 → Quenched Molecular dynamics using the Verlet algorithm, and stopping each atom for which the scalar product of velocity and force is negative. The only related parameter is the time step (dtion). The goal is not to produce a realistic dynamics, but to go as fast as possible to the minimum. For this purpose, it is advised to set all the masses to the same value (for example, use the Carbon mass, i.e. set amu to 12 for all type of atoms). Purpose: Structural optimization Cell optimization: No (Use optcell = 0 only) Related variables: time step dtion, index of atoms fixed iatfix

  • 9 → Langevin molecular dynamics. Purpose: Molecular dynamics Cell optimization: No (Use optcell = 0 only) Related variables: time step (dtion), temperatures (mdtemp) and friction coefficient (friction).

  • 12 → Isokinetic ensemble molecular dynamics. The equation of motion of the ions in contact with a thermostat are solved with the algorithm proposed by Zhang [J. Chem. Phys. 106, 6102 (1997)], as worked out by Minary et al [J. Chem. Phys. 188, 2510 (2003)]. The conservation of the kinetic energy is obtained within machine precision, at each step. Purpose: Molecular dynamics Cell optimization: No (Use optcell=0 only)

  • 13 → Isothermal/isenthalpic ensemble. The equation of motion of the ions in contact with a thermostat and a barostat are solved with the algorithm proposed by Martyna, Tuckermann Tobias and Klein [Mol. Phys., 1996, p. 1117]. If optcell=1 or 2, the mass of the barostat (bmass) must be given in addition. Purpose: Molecular dynamics Cell optimization: Yes (if optcell/=0) Related variables: The time step (dtion), the temperatures (mdtemp), the number of thermostats (nnos), and the masses of thermostats (qmass).

  • 22 → Conduct structural optimization using the Limited-memory Broyden-Fletcher-Goldfarb-Shanno minimization (L-BFGS) [Nocedal1980]. The working routines were based on the original implementation of J. Nocedal available on netlib.org. This algorithm can be much better than the native implementation of BFGS in ABINIT (ionmov = 2) when one approaches convergence, perhaps because of better treatment of numerical details. Purpose: Structural optimization Cell optimization: Yes (if optcell/=0) Related variables:

  • 24 → Simple constant energy molecular dynamics using the velocity Verlet symplectic algorithm (second order), see [Hairer2003]. The only related parameter is the time step (dtion). Purpose: Molecular dynamics Cell optimization: No (Use optcell = 0 only) Related variables: time step dtion

  • 25 → Hybrid Monte Carlo sampling of the ionic positions at fixed temperature and unit cell geometry (NVT ensemble). The underlying molecular dynamics corresponds to ionmov=24. The related parameters are the time step (dtion) and thermostat temperature (mdtemp). Within the HMC algorithm [Duane1987], the trial states are generated via short NVE trajectories (ten ionmov=24 steps in current implementation). The initial momenta for each trial are randomly sampled from Boltzmann distribution, and the final trajectory state is either accepted or rejected based on the Metropolis criterion. Such strategy allows to simultaneously update all reduced coordinates, achieve higher acceptance ratio than classical Metropolis Monte Carlo and better sampling efficiency for shallow energy landscapes [Prokhorenko2018]. Purpose: Monte Carlo sampling Cell optimization: No (Use optcell = 0 only) Related variables: time step dtion, thermostat temperature mdtemp,

  • 101 → NVE ensemble with velocity Verlet algorithm [Swope1982] . Purpose: Molecular dynamics Cell optimization: No (Use optcell=0 only) Related variables: The time step (dtion), the temperatures (temperature). The time step should be small enough to make the energy conserved. The temperature is set to intialize the velocities of the atoms, which is in principle not preserved during the NVE run.

  • 102 → NVT ensemble with Langevin algorithm. [Vanden2006] . Purpose: Molecular dynamics Cell optimization: No (Use optcell=0 only) Related variables: The time step (dtion), the temperatures (temperature), the friction latt_friction. The atoms are coupled to the heat bath, which is represented by a gauss noise in the forces, whose amplitude is defined by the temperature, and a friction term.

  • 103 → NVT ensemble. The temperature is approached by scaling the velocity of atoms. The method is proposed by Berendsen et al. in J. Chem. Phys., 81 3684–3690 (1984) [Berendsen1984]. Note that this method does NOT generate properly the thermostated ensemble. It does not have the correct distribution of the kinetic energy but have the correct average. However, it approches the target temperature exponentially without oscillation, for which the steps can be easily controlled. Purpose: Molecular dynamics Cell optimization: No (Use optcell=0 only) Related variables: The time step (dtion), the temperatures (temperature), the ion relaxation time latt_taut.

  • 120 → Dummy mover. Atoms does not move. For testing only.

energy_reference

Mnemonics: Energy of the refences structure
Characteristics: ENERGY
Mentioned in topic(s): topic_LatticeModel
Variable type: real
Dimensions: scalar
Default value: 0.0
Added in version: before_v9

Test list (click to open). Moderately used, [11/58] in all multibinit tests, [0/10] in multibinit tutorials

Set the energy of the reference structure (from the DFT calculation) if the energy of the reference is not specified in the DDB, (for example if the DDB file of the ground states is not merged), or not specified in the XML file), (by default in Hartree).

fit_anhastrain

Mnemonics: FIT ANHARmonic STRAIN coefficients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Flag to activate the anharmonic strain. This option will add coefficients like (eta^4)

fit_bancoeff

Mnemonics: FIT BANed COEFFicients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: (fit_nbancoeff)
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Indices of the banned coefficients during the fit process of the model

fit_coeff

Mnemonics: FIT anharmonic COEFFficients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [13/58] in all multibinit tests, [1/10] in multibinit tutorials

  • 0 → do not active the fit process

  • 1 → Activate the fit process. This option will first generate a set of coefficients if fit_generatecoeff is set to one. This generation is mainly parametrized by fit_rangepower and fit_cutoff. You can also provided a list of coefficients with the model_anharmonic.MXL (see multibinit help file). Then the fit process will select the coefficients one by one up to fit_ncoeff (see this paper for the details of the procedure).

  • -1 → only for developers, print the files for the scripts

fit_cutoff

Mnemonics: FIT CUT-OFF of the anharmonic phonon interaction
Mentioned in topic(s): topic_FitProcess
Variable type: real
Dimensions: scalar
Default value: Unit cell
Added in version: before_v9

Test list (click to open). Moderately used, [11/58] in all multibinit tests, [1/10] in multibinit tutorials

Cut-off for the anharmonic phonon interaction (in Bohr)

fit_dispterms

Mnemonics: FIT anharmonic Strain-Phonon COUPLING coefficients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Moderately used, [2/58] in all multibinit tests, [1/10] in multibinit tutorials

Flag to activate the generation of pure displacement coefficients. This option will generate coefficients like (Sr-Ti)^2*(Sr-O), where only atomic displacements occur.

Default value: 1 -> displacement terms are generated.

fit_efs

Mnemonics: FIT on Energy, Forces, and or, Stresses
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: (3)
Default value: [0, 1, 1]
Added in version: v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specifies on which first-principles quantities the anharmonic coefficients will be fitted. The first number flags the fitting on the energies, the second the fitting on the forces, and the third on the stressses.

Default value is 0 1 1, so anharmonic coefficients get fitted on Forces and Stresses but not on energies

fit_factors

Mnemonics: FIT FACTORS for Goal Function of Energy, Forces, and Stresses
Mentioned in topic(s): topic_FitProcess
Variable type: real
Dimensions: (3)
Default value: [1, 1, 1]
Added in version: v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Specifies three factors for Energy, Forces and Stresses in the calcluation of the Goal Function which is to be minimized during the fit process allowing to change the relative weight of the three quantities.

Default value is 1 1 1, equally balancing energy, forces and stresses.

fit_fixcoeff

Mnemonics: FIT FIXed COEFFicients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: (fit_nfixcoeff)
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [5/58] in all multibinit tests, [0/10] in multibinit tutorials

Indices of the imposed coefficients during the fit process for the model:

fit_generatecoeff

Mnemonics: FIT GENERATE anharmonic COEFFicient
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Flag to activate the generation of the anharmonic coefficient for the fit process

Related variables: The power range of the coefficients (fit_rangepower), the cut off of the interactions (fit_cutoff), the flag to add anharmonic strain (fit_anhastrain), the flag to add phonon strain coupling (fit_spcoupling)

fit_iatom

Mnemonics: FIT anharmonic terms around ATOM I
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [13/58] in all multibinit tests, [1/10] in multibinit tutorials

Gives the index of the atom in the reference structure around which the anharmonic terms will be generated. If 0 (default) a loop over all atoms in the reference structure will be perforemed and fit_ncoeff coefficienst will be fitted and selected per atom. If -1 all possible cross terms will be generated (e.G. (A_x-B_x)2*(C_y-D_y)1. This options generates much more terms.

fit_imposecoeff

Mnemonics: FIT Number of IMPOSEd COEFFicients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: (fit_nimposecoeff)
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Indices of the imposed coefficients with fixed coefficient value during the fit process for the model.

fit_initializedata

Mnemonics: FIT INITIALIZE DATA for the fit
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Flag to de/activate the precomputing and storage of all the data for the fit, it will reduce the computation time but increase a lot the memory…

fit_nbancoeff

Mnemonics: FIT Number of BANed COEFFicients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Number of imposed coefficients during the fit process of the model:

  • 0 → do not ban coefficients

  • n → ban n coefficients (requires fit_bancoeff input variable)

fit_ncoeff

Mnemonics: FIT Number of COEFFicients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [13/58] in all multibinit tests, [1/10] in multibinit tutorials

Give the number of anharmonic coefficients to add in the model during the fit process

fit_ncoeff_per_iatom

Mnemonics: FIT Number of COEFFicients per Irreducible ATOM
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Give the number of anharmonic coefficients per symmetric irreducible atom to add during fit process. fit_ncoeff/(nirred_atoms*fit_ncoeff_per_iatom) gives the number of fitting loops performed during the fit process, where in each loop fit_ncoeff_per_iatom coefficients for each irreducible atom will be added to the anharmonic potential.

fit_nfixcoeff

Mnemonics: FIT Number of FIXed COEFFicients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [6/58] in all multibinit tests, [0/10] in multibinit tutorials

Number of imposed coefficients during the fit process for the model:

  • -1 → fix all the coefficients

  • 0 → do not fix coefficients

  • n → fix n coefficients (requires fit_fixcoeff input variable)

fit_nimposecoeff

Mnemonics: FIT Number of IMPOSEd COEFFicients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Number of coefficients imposed with fixed value as in the input xml during the fit process for the model:

  • -1 → fix all the coefficients

  • 0 → do not fix coefficients

  • n → fix n coefficients (requires fit_imposecoeff input variable)

fit_rangepower

Mnemonics: FIT RANGE POWER for the coefficients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: (2)
Default value: 3 4
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Set the range of the powers for the anharmonic coefficients

fit_spc_maxs

Mnemonics: FIT Strain Phonon Coupling maximum Strain
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Set maximum power of strain body in strain-phonon coupling terms.

fit_spcoupling

Mnemonics: FIT anharmonic Strain-Phonon COUPLING coefficients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Flag to activate the strain phonon coupling. This option will add coefficients like (Sr-Ti)^1 (eta^4)

fit_tolmsde

Mnemonics: FIT TOLerance on Mean Standard Deviation of the Energy
Mentioned in topic(s): topic_FitProcess
Variable type: real
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Tolerance of the fit based on the Mean Standard Deviation of the Energy in (meV/atm)

fit_tolmsdf

Mnemonics: FIT TOLerance on Mean Standard Deviation of the Forces
Mentioned in topic(s): topic_FitProcess
Variable type: real
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Tolerance of the fit based on the Mean Standard Deviation of the Forces (eV2/A2)

fit_tolmsdfs

Mnemonics: FIT TOLerance on Mean Standard Deviation of the Forces and Stresses
Mentioned in topic(s): topic_FitProcess
Variable type: real
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Tolerance of the fit based on the Mean Standard Deviation of the Forces and Sressses (eV2/A2)

fit_tolmsds

Mnemonics: FIT TOLerance on Mean Standard Deviation of the Stresses
Mentioned in topic(s): topic_FitProcess
Variable type: real
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Tolerance of the fit based on the Mean Standard Deviation of the Stresses in (eV2/A2)

latt_anharm_pot_fname

Mnemonics: LATTice HARMornic POTential File NAME
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: string
Dimensions: scalar
Default value:
Added in version: 9.8

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify the input coefficients from fitted polynomial in multibinit lattice calculation, which can be a xml file. The string must be enclosed between quotation marks:

lat_anharm_pot_fname "BaTiO3_coeff.xml"

latt_friction

Mnemonics: LATTice dynamics FRICTION parameter
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0.0001
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Parameter of the friction coefficient used in Langevin dynamics dynamics =102. Typical value is 1e-4 to 1e-2.

latt_harm_pot_fname

Mnemonics: LATTice HARMonic POTential File NAME
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: string
Dimensions: scalar
Default value:
Added in version: 9.8

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify the input derivative database of reference structure in multibinit lattice calculation, which can be a DDB file or a xml file. The string must be enclosed between quotation marks:

latt_harm_pot_fname "BaTiO3.ddb"

latt_pot_fname

Mnemonics: LATTice POTential FileNAME
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: string
Dimensions: scalar
Default value:
Added in version: 9.8

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify the lattice potential file name in the multibinit lattice dynamics calculation, which can be a netcdf file. This variable is only used in the harmonic-only lattice potential for testing only. The string must be enclosed between quotation marks:

latt_pot_fname "BaTiO3.nc"

latt_taup

Mnemonics: LATTice dynamics relaxation time TAUP
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 1000
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Parameter used in Berendsen lattice dynamics dynamics =103, in which the pressure is relaxed exponentially to the target temperature, with the characteristic time of latt_taup. The default unit is atomic unit. But it is possible to use the second as the unit by adding Second or S at the end of the line, for example:

latt_taup 1d-15 S

latt_taut

Mnemonics: LATTice dynamics relaxation time TAUT
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 1000
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Parameter used in Berendsen lattice dynamics dynamics =102 and 103, in which the temperature is relaxed exponentially to the target temperature, with the characteristic time of latt_taut. The default unit is atomic unit. But it is possible to use the second as the unit by adding Second or S at the end of the line, for example:

latt_taut 1d-15 S

latt_test_set_fname

Mnemonics: LATTice potential TEST SET File NAME
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: string
Dimensions: scalar
Default value:
Added in version: 9.8

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify the test set file name for building multibinit lattice potential, which is usually a abinit molecular dynamics history netcdf file. The string must be enclosed between quotation marks:

latt_test_set_fname "BaTiO3_md_hist.nc"

latt_training_set_fname

Mnemonics: LATTice potential TRAINING SET File NAME
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: string
Dimensions: scalar
Default value:
Added in version: 9.3.3

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify the training set file name for building multibinit lattice potential, which is usually a abinit molecular dynamics history netcdf file. The string must be enclosed between quotation marks:

latt_training_set_fname "BaTiO3_md_hist.nc"

lwf_constraint

Mnemonics: Lattice Wannier Function use CONSTRAINT
Mentioned in topic(s): topic_LWFModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: 9.8

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Whether to use constraint in Lattice Wannier function dynamics. The constraints are defined in a LWF initial state file by three parameters: n_fixed_lwf: number of fixed LWF. fixed_lwf_ids: indices of fixed LWFs. fixed_lwf_values: values of fixed LWFs.

lwf_dt

Mnemonics: Lattice Wannier Function Delta Time
Mentioned in topic(s): topic_LWFModel
Variable type: real
Dimensions: scalar
Default value: 100
Added in version: 9.8

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Time step for lwf dynamics. Default value is 100. Default unit is atomic unit (2.419e-17 s). S, Sec or Second can be appended as unit. (e.g. 1e-16 Sec).

lwf_dynamics

Mnemonics: Lattice Wannier Function DYNAMICS
Mentioned in topic(s): topic_LWFModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: 9.8

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Kind of LWF dynamics to run. Currently there is only the option 3.

  • 0: Do not run LWF dynamics.

  • 3: Run NVT LWF dynamics with the Berendsen thermalstat.

lwf_init_hist_fname

Mnemonics: LWF INITIAL state HISTory file name
Mentioned in topic(s): topic_LWFModel
Variable type: string
Dimensions: scalar
Default value:
Added in version: 9.8

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify the initial state of the multibinit LWF dynamics calculation, which can be a lwf_hist netcdf file, usually generated from previous LWF dynamics calculations. It is used when lwf_init_state=4 The string must be enclosed between quotation marks, for example:

lwf_init_hist_fname "last_step_lwf_hist.nc"

lwf_init_state

Mnemonics: Lattice Wannier Function INITial STATE
Mentioned in topic(s): topic_LWFModel
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Flag to initialize spin state.

  • 1 → The LWF amplitudes are homogenous random numbers between -0.1 to 0.1 Bohr.

  • 2 → The LWF amplitudes are 0.

  • 4 → Restart from an input spin hist file, as specified in lwf_init_hist_fname.

lwf_nctime

Mnemonics: Lattice Wannier function dynamics NetCdf write per number of TIME steps
Mentioned in topic(s): topic_LWFModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Write LWF amplitude into netcdf file in every lwf_nctime of spin dynamics time steps.

lwf_ntime

Mnemonics: Lattice Wannier function dynamics total Number of TIME steps
Mentioned in topic(s): topic_LWFModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: 9.8

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Total number of lattice Wannier function dynamics time steps.

lwf_pot_fname

Mnemonics: Lattice Wannier function POTential File NAME
Mentioned in topic(s): topic_LWFModel
Variable type: string
Dimensions: scalar
Default value:
Added in version: 9.8

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify the LWF potential file name in the multibinit lwf dynamics calculation, which is a netcdf file. The string must be enclosed between quotation marks:

lwf_pot_fname "BaTiO3_lwf_pot.nc"

lwf_taut

Mnemonics: Lattice Wannier function dynamics relaxation time TAUT
Mentioned in topic(s): topic_LWFModel
Variable type: integer
Dimensions: scalar
Default value: 1000
Added in version: 9.8

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Parameter used in Berendsen lattice dynamics lwf_dynamics = 3, in which the temperature is relaxed exponentially to the target temperature, with the characteristic time of lwf_taut. The default unit is atomic unit. But it is possible to use the second as the unit by adding Second or S at the end of the line, for example:

lwf_taut 1d-15 S

lwf_temperature_end

Mnemonics: Lattice Wannier function TEMPERATURE END
Mentioned in topic(s): topic_LWFModel
Variable type: real
Dimensions: scalar
Default value: 0.0
Added in version: 9.8

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

End point of variable temperature LWF dynamics calculation (see lwf_var_temperature) in LWF dynamics calculation.

lwf_temperature_nstep

Mnemonics: Lattice Wannier function TEMPERATURE Number of STEPs
Mentioned in topic(s): topic_LWFModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: 9.8

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Number of steps in the variable temperature LWF dynamics calculation (see lwf_var_temperature) in lwf dynamics calculation.

lwf_temperature_start

Mnemonics: Lattice Wannier function TEMPERATURE START
Mentioned in topic(s): topic_LWFModel
Variable type: real
Dimensions: scalar
Default value: 0.0
Added in version: 9.8

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Start point of variable temperature LWF dynamcis calculation (see lwf_var_temperature) in lwf dynamics calculation.

lwf_var_temperature

Mnemonics: Lattice Wannier function VARiable TEMPERATURE
Mentioned in topic(s): topic_LWFModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: 9.8

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Switch for variable temperature calculation in LWF dynamics. 0: off. 1: on. If switched on, a series of LWF dynamics calculation with temperatures from lwf_temperature_start to lwf_temperature_end, with number of steps lwf_temperature_nstep will be done. The corresponding _lwf_hist.nc file has the corresponding temperature in the filename.

ncell

Mnemonics: Number of Cell
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: (3)
Default value: [6, 6, 6]
Added in version: before_v9

Test list (click to open). Very frequently used, [47/58] in all multibinit tests, [8/10] in multibinit tutorials

Give the size of the supercell for the dynamics

ncellmat

Mnemonics: Number of superCELL MATtrix
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: (3,3)
Default value: [[1, 0, 0], [0, 1, 0], [0, 0, 1]]
Added in version: 9.5.0

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Give the size of the supercell for the dynamics in the format of a matrix. Currently allowed in spin dynamics and spin and LWF dynamics. It will override the ncell if specified.

ncoeff

Mnemonics: Number of anharmonic COEFFicients
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [19/58] in all multibinit tests, [1/10] in multibinit tutorials

Set the number of anharmonic coefficients in the model. This number have to be in agreement with the number of coefficients present in the XML file.

If ncoeff /= 0, coefficients have to be present in the input files

nctime

Mnemonics: NetCdf TIME between output of molecular dynamics informations
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Moderately used, [16/58] in all multibinit tests, [5/10] in multibinit tutorials

Set the number of step between output the molecular dynamics informations in the NetCDF file

ngqpt

Mnemonics: Number of Grids points for Q PoinTs
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: (3)
Default value: 3*1
Added in version: before_v9

Test list (click to open). Moderately used, [16/58] in all multibinit tests, [4/10] in multibinit tutorials

The Monkhorst-Pack grid linear dimensions, for the DDB (coarse grid).

nnos

Mnemonics: Number of NOSe masses
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

See nnos

nqshft

Mnemonics: Number of Q SHiFTs
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

The number of vector shifts of the simple Monkhorst and Pack grid, needed to generate the coarse grid of q points (for the series of fine grids, the number of shifts it is always taken to be 1). Usually, put it to 1. Use 2 if BCC sampling (Warning: not BCC lattice, BCC sampling), and 4 for FCC sampling (Warning: not FCC lattice, FCC sampling).

ntime

Mnemonics: Number of TIME step
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 200
Added in version: before_v9

Test list (click to open). Very frequently used, [39/58] in all multibinit tests, [6/10] in multibinit tutorials

Number of step for the dynamics.

opt_coeff

Mnemonics: OPTimize Cofficients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: (opt_ncoeff)
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Indices of the terms to refit in the effective potential.

opt_effpot

Mnemonics: OPTimize EFFective POTential
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials
  • 0 → Nothing.
  • 1 → Turn on reading of optimization of effective potential keywords (opt_). The optimization process gives the user the ability to refit the coefficients of specified terms with respect to the training set while keeping the rest fixed.

Related variables: The number of coefficients to refit (opt_ncoeff), the indices of the coefficients to optimize (opt_coeff).

opt_factors

Mnemonics: FACTORS for Goal Function of Energy, Forces, and Stresses during optimization of coefficients
Mentioned in topic(s): topic_FitProcess
Variable type: real
Dimensions: (3)
Default value: [1, 1, 1]
Added in version: v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specifies three factors for Energy, Forces and Stresses in the calcluation of the Goal Function which is to be minimized during the optimization process allowing to change the relative weight of the three quantities.

Default value is 1 1 1, equally balancing energy, forces and stresses.

opt_ncoeff

Mnemonics: OPTimize NUMBER of COEFFicients
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials
  • Number of anharmonic terms to refit in the effective potential. Related variables: opt_coeff

optcell

Mnemonics: OPTimize the CELL shape and dimensions
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [15/58] in all multibinit tests, [1/10] in multibinit tutorials

See optcell

outdata_prefix

Mnemonics: OUTput DATA PREFIX
Mentioned in topic(s): topic_Control
Variable type: string
Dimensions: scalar
Default value: None
Added in version: 9.8.0

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Prefix for output files. Replaces the analogous entry in the obsolete files_file . This variable is used when MULTIBINIT is executed with the new syntax:

multibinit run.abi > run.log 2> run.err &

If this option is not specified, a prefix is automatically constructed from the input file name provided the filename ends with an extension, e.g. .ext. (.abi is recommended) If the input filename does not have a file extension, a default is provided.

Example:

outdata_prefix = "t01_o"

See also outdata_prefix@abinit and outdata_prefix@anaddb

prt_gf_csv

Mnemonics: Print the Goal-Function values in a CSV file
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials
  • 0 → do nothing (Default)
  • 1 → Print the Goal-Function Values (GF) for all coefficients on a given processor at a given fit iteration into a csv file. Each iteration each processor prints a csv file. The colums are the GF on Energy, Force+Stresses, Forces, Stresses.

prt_model

Mnemonics: PRinT the MODEL
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Very frequently used, [54/58] in all multibinit tests, [7/10] in multibinit tutorials
  • 0 → do nothing (Default).

  • 1 → Generate the XML file with:

     * The system definition and the model (Harmonic + Anharmonic) in _model.xml

  • 2 → Generate two XML files with:

     * The system definition and the model (Harmonic) in _sys.XML
 * The model (Anharmonic) in _coeffs.xml

  • 3 → Generate only one XML file with:

     * The system definition and the model (Harmonic) in _sys.XML

  • 4 → Generate only one XML file with:

     * The model (Anharmonic) in _coeffs.xml

    qmass

Mnemonics: Q thermostat MASS
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: real
Dimensions: (nnos)
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

See qmass

randomseed

Mnemonics: RANDOM SEED
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: 9.8

Test list (click to open). Moderately used, [11/58] in all multibinit tests, [4/10] in multibinit tutorials

Random seed to be used in Multibinit spin/LWF dynamics. It should be 0, or a large positive integer. The default value 0 means it will use the current clock time. DO NOT set this number unless you want to repeat the previous result. If a series of dynamics is done with the same seed, the results could be wrong due to the artificial periodicity of the random number that is generated. Even randomseed@multibinit is set, it is not guranteed that the previous result can be recovered, as the generation of numbers is also affected by the number of processors, type of type of CPU, compiler, and version of MULTIBINIT.

restartxf

Mnemonics: RESTART from (X,F) history
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [3/58] in all multibinit tests, [0/10] in multibinit tutorials

See restartxf

sel_efs

Mnemonics: Select on Energy, Forces, and or, Stresses
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: (3)
Default value: [0, 1, 1]
Added in version: v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specifies on which goal function quantities the anharmonic coefficients will be selected. The first number flags the selecting on the energies, the second the fitting on the forces, and the third on the stressses.

Default value is 0 1 1, so anharmonic coefficients get selected on Forces and Stresses but not on energies

slc_coupling

Mnemonics: SpinLatticeCoupling_Coupling
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: 9.0.0

Test list (click to open). Moderately used, [3/58] in all multibinit tests, [0/10] in multibinit tutorials

Which spin-lattice coupling terms are used in the calculation, different terms can be combined in a binary fashion, i.e. 1010 turns on all terms quadratic in spin.

  • 0 → No coupling.

  • 0001 → Coupling term linear in spin and lattice coordinate

  • 0010 → Coupling term quadratic in spin and linear in lattice coordinate

  • 0100 → Coupling term linear in spin and quadratic in lattice coordinate

  • 1000 → Coupling term quadratic in spin and lattice coordinate

slc_pot_fname

Mnemonics: SLC POTential FileNAME
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: string
Dimensions: scalar
Default value:
Added in version: 9.3.3

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify the spin-lattice-coupling potential file name in the coupled spin-lattice multibinit dynamics calculation, which can be a netcdf file. The string must be enclosed between quotation marks:

slc_pot_fname "BaTiO3_slc.nc"

spin_calc_thermo_obs

Mnemonics: SPIN CALCulate THERMO dynamics OBServables
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Flag to calculate spin thermo dynamics observables, including the specific heat, magnetic susceptibility, Binder U4 value. It’s recommend to always calculate these observables.

  • 0 → do not calculate.

  • 1 → calculate.

spin_damping

Mnemonics: SPIN gilbert DAMPING factor
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: -1.0
Added in version: before_v9

Test list (click to open). Moderately used, [3/58] in all multibinit tests, [0/10] in multibinit tutorials

Gilbert damping factor in LLG equation for spin dynamics.

  • negative value → use damping factor from spin xml file.

  • positive value → use as damping factor. The value should be between 0.0 and 1.0 (both included).

spin_dt

Mnemonics: SPIN Delta Time
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: 100
Added in version: before_v9

Test list (click to open). Moderately used, [9/58] in all multibinit tests, [3/10] in multibinit tutorials

Time step for spin dynamics. Default value is 100. Default unit is atomic unit (2.419e-17 s). S, Sec or Second can be appended as unit. (e.g. 1e-16 Sec).

spin_dynamics

Mnemonics: SPIN DYNAMICS
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [9/58] in all multibinit tests, [3/10] in multibinit tutorials

Flag to run spin dynamics.

  • 0 → Do not run spin dynamics.

  • 1 → Run spin dynamics with HeunP integration method.

  • 2 → Run spin dynamics with Depondt-Mertens method [Depondt2009].

  • 3 → Run Monte Carlo.

  • 20 → Dummy mover. Spin will not rotate. For test only.

The HeunP method does less computation for each step, whereas the Depondt-Mertens method allow larger time step. For system with very simple interaction terms, HeunP could be faster. Otherwise, use Depondt-Mertens method can be more efficient.

spin_init_hist_fname

Mnemonics: SPIN INITIAL state HISTory file name
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: string
Dimensions: scalar
Default value:
Added in version: 9.3.3

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify the initial state of the multibinit spin dynamics calculation, which can be a spin_hist netcdf file, usually generated from previous spin dynamics calculations. It is used when spin_init_state=4 The string must be enclosed between quotation marks, for example:

spin_init_hist_fname "last_step_spin_hist.nc"

spin_init_orientation

Mnemonics: SPIN INITial ORIENTATION
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: (3)
Default value: [0, 0, 1]
Added in version: before_v9

Test list (click to open). Moderately used, [3/58] in all multibinit tests, [0/10] in multibinit tutorials

Spin initial orientation. It is used for setting the initial spin in a supercell. For a spin in a cell labeled with R, the rotation angle is 2\pi Q\cdot R from the initial orientation along the rotate axis. Default is along z(0,0,1) direction.

spin_init_qpoint

Mnemonics: SPIN INITial QPOINT
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: (3)
Default value: [0, 0, 0]
Added in version: before_v9

Test list (click to open). Moderately used, [4/58] in all multibinit tests, [1/10] in multibinit tutorials

Spin wave vector. It is used for setting the initial spin in a supercell. For a spin in a cell labeled with R, the rotation angle is 2\pi Q\cdot R from the initial orientation along the rotate axis. Default is Gamma (0, 0, 0).

spin_init_rotate_axis

Mnemonics: SPIN INITial ROTATE AXIS
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: (3)
Default value: [1, 0, 0]
Added in version: before_v9

Test list (click to open). Moderately used, [3/58] in all multibinit tests, [0/10] in multibinit tutorials

Spin initial rotate axis. It is used for setting the initial spin in a supercell. For a spin in a cell labeled with R, the rotation angle is 2\pi Q\cdot R from the initial orientation along the rotate axis. Default is along x axis (1,0,0).

spin_init_state

Mnemonics: SPIN INITial STATE
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Moderately used, [9/58] in all multibinit tests, [3/10] in multibinit tutorials

Flag to initialize spin state.

spin_mag_field

Mnemonics: SPIN Magnetic Field
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: (3)
Default value: [0, 0, 0]
Added in version: before_v9

Test list (click to open). Moderately used, [7/58] in all multibinit tests, [1/10] in multibinit tutorials

External magnetic field. Unit: Tesla.

spin_nctime

Mnemonics: SPIN NetCdf write per number of TIME steps
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [9/58] in all multibinit tests, [3/10] in multibinit tutorials

Write spin into netcdf file in every spin_nctime of spin dynamics time steps.

spin_ntime

Mnemonics: SPIN dynamics total Number of TIME steps
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [9/58] in all multibinit tests, [3/10] in multibinit tutorials

Total number of spin dynamics time steps.

spin_ntime_pre

Mnemonics: SPIN dynamics total Number of TIME steps for PREparing
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [4/58] in all multibinit tests, [3/10] in multibinit tutorials

Total number of spin dynamics time steps for preparing the system. The results of these time step are not written to trajectory spinhist.nc file, And they are not used for calculating the observables.

spin_pot_fname

Mnemonics: SPIN POTential File NAME
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: string
Dimensions: scalar
Default value:
Added in version: 9.3.3

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Specify the spin potential file name in the multibinit spin dynamics calculation, which can be either a xml or a netcdf file. The string must be enclosed between quotation marks:

spin_pot_fname "Fe.xml"

spin_projection_qpoint

Mnemonics: SPIN PROJECTION QPOINT
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: (3)
Default value: [0, 0, 0]
Added in version: before_v9

Test list (click to open). Moderately used, [3/58] in all multibinit tests, [1/10] in multibinit tutorials

Spin wave vector. It is used for getting the total spin. M_{tot}=\sum_i M_i exp(i q \cdot R_i). The unit is the reciprocal lattice vectors of the unitcell. Default is Gamma. (0, 0, 0)

spin_sia_add

Mnemonics: SPIN Single Ion Anistropy ADD
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [2/58] in all multibinit tests, [2/10] in multibinit tutorials

Add single ion anisotropy term to the spin model hamiltonian. with user defined values (see spin_sia_k1amp and spin_sia_k1dir.

  • 0 → Do not add, use the term defined in the spin model xml file.

  • 1 → Override the term in spin model xml file.

  • 2 → Add to the value defined in spin model xml file.

Default value: 0.

spin_sia_k1amp

Mnemonics: SPIN Single Ion Anistropy K1 AMPtitude
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: 0.0
Added in version: before_v9

Test list (click to open). Moderately used, [2/58] in all multibinit tests, [2/10] in multibinit tutorials

User defined amplitude of single ion anistropy. Only used when spin_sia_add is not 0. The direction is defined with spin_sia_k1dir. The unit is Ha. To use eV or Ry as unit, put eV or Ry at the end.

spin_sia_k1dir

Mnemonics: SPIN Single Ion Anistropy K1 DIRection
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: (3)
Default value: [0.0, 0.0, 1.0]
Added in version: before_v9

Test list (click to open). Moderately used, [2/58] in all multibinit tests, [2/10] in multibinit tutorials

User defined direction of single ion anistropy. Only used when spin_sia_add is not 0. It will be automatically normalized to 1.0. The amplitude is defined with spin_sia_k1amp. Default value: [0.0, 0.0,1.0].

spin_temperature

Mnemonics: SPIN TEMPERATURE
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: 325
Added in version: before_v9

Test list (click to open). Moderately used, [9/58] in all multibinit tests, [3/10] in multibinit tutorials

Temperature of spin for spin dynamics. Unit: Kelvin. Default value: 325.

spin_temperature_end

Mnemonics: SPIN TEMPERATURE END
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: 0.0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

End point of variable temperature spin dynamics calculation (see spin_var_temperature) in spin dynamics calculation.

spin_temperature_nstep

Mnemonics: SPIN TEMPERATURE Number of STEPs
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Number of steps in the variable temperature spin dynamics calculation (see spin_var_temperature) in spin dynamics calculation.

spin_temperature_start

Mnemonics: SPIN TEMPERATURE START
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: 0.0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Start point of variable temperature spin dynamcis calculation (see spin_var_temperature) in spin dynamics calculation.

spin_var_temperature

Mnemonics: SPIN VARiable TEMPERATURE
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [1/10] in multibinit tutorials

Switch for variable temperature calculation. 0: off. 1: on. If switched on, a series of spin dynamics calculation with temperatures from spin_temperature_start to spin_temperature_end, with number of steps spin_temperature_nstep will be done. The corresponding _spinhist.nc file has the corresponding temperature in the filename.

spin_write_traj

Mnemonics: SPIN WRITE TRAJectory to spinhist.nc file
Mentioned in topic(s): topic_SpinDynamicsMultibinit
Variable type: integer
Dimensions: scalar
Default value: 1
Added in version: before_v9

Test list (click to open). Moderately used, [4/58] in all multibinit tests, [1/10] in multibinit tutorials

Switch for writting of spin trajectory file. 0: off. 1 on. The trajectory is needed for postprocessing of correlation functions.

strfact

Mnemonics: STRess FACTor
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: 100.0
Added in version: v9.1

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

See strfact

strtarget

Mnemonics: STRess TARGET
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: real
Dimensions: (6)
Default value: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
Added in version: before_v9

Test list (click to open). Moderately used, [3/58] in all multibinit tests, [0/10] in multibinit tutorials

See strtarget

temperature

Mnemonics: molecular dynamics TEMPERATURE (in Kelvin)
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: 325
Added in version: before_v9

Test list (click to open). Very frequently used, [39/58] in all multibinit tests, [6/10] in multibinit tutorials

Give the temperature of the dynamics in Kelvin

test_effpot

Mnemonics: TEST EFFective POTential
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials
  • 0 → nothing.
  • 1 → Evaluate the effective potential with respect to given test-set and calculate mean square differences between ab-initio energy/forces and model energy/forces

test_prt_ph

Mnemonics: Prt test-set evaluation into file ph_test.nc
Mentioned in topic(s): topic_LatticeModel
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Moderately used, [1/58] in all multibinit tests, [0/10] in multibinit tutorials

Flag to activate the printing of the evaluation of the effective potential on to a test set into a seperate netcdf file called ph_test.nc.

Forces, Energies, Stresses and Atomic Positions are written in ph_test.nc.

tolmxf

Mnemonics: TOLerance on the MaXimal Force
Mentioned in topic(s): topic_DynamicsMultibinit
Variable type: real
Dimensions: scalar
Default value: 2e-05
Added in version: v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

Sets a maximal absolute force tolerance (in hartree/Bohr) below which BFGS structural relaxation iterations will stop. Corresponds to tolmxf of Abinit.

ts_option

Mnemonics: fit Training Set OPTION
Mentioned in topic(s): topic_FitProcess
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Test list (click to open). Rarely used, [0/58] in all multibinit tests, [0/10] in multibinit tutorials

  • 0 → the Training is hist from ABINIT

  • 1 → the Training contains -1 * stress (usualy output from VASP)