vdw input variables¶
This document lists and provides the description of the name (keywords) of the vdw input variables to be used in the input file for the abinit executable.
irdvdw¶
Mnemonics: Integer that governs the ReaDing of _VDW files
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: scalar
Default value: 0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc > 0, to read previously calculated vdWDF variables. Supported values:
 0: do not read vdWDF variables
 1: read vdWDF variables
prtvdw¶
Mnemonics: PRinT Van Der Waals file
Characteristics: DEVELOP
Mentioned in topic(s): topic_printing
Variable type: integer
Dimensions: scalar
Default value: 0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Print out a NetCDF file containing a vdWDF kernel.
vdw_df_acutmin¶
Mnemonics: vdWDF MINimum Angular CUToff
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 10
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build angular meshes for the vdWDF kernel.
vdw_df_aratio¶
Mnemonics: vdWDF Angle RATIO between the highest and lowest angles.
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 30
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build angular meshes for the vdWDF kernel.
vdw_df_damax¶
Mnemonics: vdWDF Delta for Angles, MAXimum
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 0.5
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build angular meshes for the vdWDF kernel.
vdw_df_damin¶
Mnemonics: vdWDF Delta for Angles, MINimum
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 0.01
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build angular meshes for the vdWDF kernel.
vdw_df_dcut¶
Mnemonics: vdWDF Dmesh CUToff
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 30
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
vdw_df_dratio¶
Mnemonics: vdWDF, between the highest and
lowest D, RATIO.
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 20
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
vdw_df_dsoft¶
Mnemonics: vdWDF Distance for SOFTening.
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 1.0
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
vdw_df_gcut¶
Mnemonics: vdWDF Gspace CUToff
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 5
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to filter the vdWDF kernel in reciprocal space.
vdw_df_ndpts¶
Mnemonics: vdWDF Number of Dmesh PoinTS
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: scalar
Default value: 20
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
vdw_df_ngpts¶
Mnemonics: vdWDF Number of Gmesh PoinTS
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: scalar
Default value: 1
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
vdw_df_nqpts¶
Mnemonics: vdWDF Number of Qmesh PoinTS
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: scalar
Default value: 30
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
vdw_df_nrpts¶
Mnemonics: vdWDF Number of RPoinTS
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: scalar
Default value: 2048
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to define the sampling of the vdWDFkernel in realspace.
vdw_df_nsmooth¶
Mnemonics: vdWDF Number of SMOOTHening iterations
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: scalar
Default value: 12
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to exponentially smoothen q near q0.
vdw_df_phisoft¶
Mnemonics: vdWDF PHI value SOFTening.
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 1.0
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
vdw_df_qcut¶
Mnemonics: vdWDF Qmesh CUToff
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 5
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
vdw_df_qratio¶
Mnemonics: vdWDF, between highest and lowest Q, RATIO.
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 20
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0,.
vdw_df_rcut¶
Mnemonics: vdWDF Realspace CUToff
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 100
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to define the vdWDF kernel cutoff radius.
vdw_df_rsoft¶
Mnemonics: vdWDF radius SOFTening.
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 0.0
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
vdw_df_threshold¶
Mnemonics: vdWDF energy calculation THRESHOLD
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 0.01
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Sets a threshold for the energy gradient that, when reached, will cause the vdWDF interactions to be calculated. Adjust it to a big value (e.g. 1e12) to enable it all along the SCF calculation. Too small values, as well as negative values, will result in the vdWDF energy contributions never being calculated.
vdw_df_tolerance¶
Mnemonics: vdWDF global TOLERANCE.
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 1e13
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
vdw_df_tweaks¶
Mnemonics: vdWDF TWEAKS.
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: scalar
Default value: 0
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, to build the vdWDF kernel.
Important
Modifying this variable will likely transform the calculated energies and their gradients into garbage. You have been warned!
vdw_df_zab¶
Mnemonics: vdWDF ZAB parameter
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 0.8491
Only relevant if: vdw_xc>0
Test list (click to open). Rarely used, [0/998] in all abinit tests, [0/117] in abinit tutorials
Used when vdw_xc>0, as introduced in [Dion2004].
vdw_nfrag¶
Mnemonics: Van Der Waals Number of interacting FRAGments
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: scalar
Default value: 1
Only relevant if: vdw_xc in [10,11]
Test list (click to open). Rarely used, [3/998] in all abinit tests, [0/117] in abinit tutorials
The absolute value of vdw_nfrag is the number of vdW interacting fragments in the unit cell. As wannierization takes place in reciprocal space, the MLWF center positions could be translated by some lattice vector from the cell where atoms are placed. If vdw_nfrag >= 1 then MLWFs are translated to the original unit cell, otherwise the program will keep the positions obtained by Wannier90. The later is usually correct if some atoms are located at the corners or at limiting faces of the unit cell.
vdw_supercell¶
Mnemonics: Van Der Waals correction from Wannier functions in SUPERCELL
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: (3)
Default value: [0, 0, 0]
Only relevant if: vdw_xc in [10,11]
Test list (click to open). Rarely used, [3/998] in all abinit tests, [0/117] in abinit tutorials
Set of dimensionless positive numbers which define the maximum multiples of the primitive translations (%rprimd) in the supercell construction. Each component of vdw_supercell indicates the maximum number of cells along both positive or negative directions of the corresponding primitive vector i.e. the components of %rprimd. In the case of layered systems for which vdW interactions occur between layers made of tightly bound atoms, the evaluation of vdW corrections coming from MLWFs in the same layer (fragment) must be avoided. Both a negative or null value for one component of vdw_supercell will indicate that the corresponding direction is normal to the layers.
vdw_tol¶
Mnemonics: Van Der Waals TOLerance
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 1e10
Only relevant if: vdw_xc == 5
Test list (click to open). Rarely used, [4/998] in all abinit tests, [0/117] in abinit tutorials
The DFTD methods [Grimme2010] dispersion potentials, vdw_xc == 5 or 6 or 7, include a pair potential. The number of pairs of atoms contributing to the potential is necessarily limited. To be included in the potential a pair of atom must have contribution to the energy larger than vdw_tol.
vdw_tol_3bt¶
Mnemonics: Van Der Waals TOLerance for 3Body Term
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: real
Dimensions: scalar
Default value: 1
Comment: Do include the 3body term in the correction
Only relevant if: vdw_xc == 6
Test list (click to open). Rarely used, [1/998] in all abinit tests, [0/117] in abinit tutorials
 v7: t97.in
Control the computation of the 3body correction inside DFTD3 dispersion correction (Grimme approach) to the total energy:
 If vdw_tol_3bt <0, no 3body correction.
 If vdw_tol_3bt >0, the 3body term is included with a tolerance = vdw_tol_3bt.
DFTD3 as proposed by S. Grimme adds two contributions to the total energy in order to take into account of the dispersion:

A pairwise potential for which the tolerance is controlled by vdw_tol

A 3body term which is obtained by summing over all triplets of atoms. Each individual contribution depends of the distances and angles between the three atoms. As it is impossible to sum over all the triplets in a periodic system, one has to define a stopping criterium which is here that an additional contribution to the energy must be higher than vdw_tol_3bt
The last term has been predicted to have an important effect for large molecules [Grimme2010]. It is however quite costly in computational time for periodic systems and seems to lead to an overestimation of lattice parameters for weakly bound systems [Grimme2011]. Still, its contribution to energy, to forces and to stress is available (not planned for elastic constants, dynamical matrix and internal strains).
vdw_typfrag¶
Mnemonics: Van Der Waals TYPe of FRAGment
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: (natom)
Default value: 1 * natom
Only relevant if: vdw_xc in [10,11]
Test list (click to open). Rarely used, [3/998] in all abinit tests, [0/117] in abinit tutorials
This array defines the interacting fragments by assigning to each atom an integer index from 1 to vdw_nfrag. The ordering of vdw_typfrag is the same as typat or xcart. Internally each MLWF is assigned to a given fragment by computing the distance to the atoms. MLWFs belong to the same fragment as their nearest atom. The resulting set of MLWFs in each interacting fragment can be found in the output file in xyz format for easy visualization.
vdw_xc¶
Mnemonics: Van Der Waals eXchangeCorrelation functional
Characteristics: DEVELOP
Mentioned in topic(s): topic_vdw
Variable type: integer
Dimensions: scalar
Default value: 0
Test list (click to open). Rarely used, [7/998] in all abinit tests, [0/117] in abinit tutorials
Selects a vanderWaals density functional to apply the corresponding correction to the exchangecorrelation energy. If set to zero, no correction will be applied. Possible values are:
 0: no correction.
 1: apply vdWDF1 (DRSLL) from [Dion2004].
 2: apply vdwDF2 (LMKLL) from [Lee2010].
 5: apply vdwDFTD2 as proposed by S. Grimme [Grimme2006] (adding a semiempirical dispersion potential). Available only for groundstate calculations and response functions; see vdw_tol variable to control convergence.
 6: apply vdwDFTD3 as proposed by S. Grimme [Grimme2010] (refined version of DFTD2). Available only for groundstate calculations and response functions; see vdw_tol variable to control convergence and vdw_tol_3bt variable to include 3body corrections.
 7: apply vdwDFTD3(BJ) as proposed by Grimme (based on BeckeJonhson method from [Becke2006]). Available only for groundstate calculations and response functions; see vdw_tol variable to control convergence.
 10: evaluate the vdW correlation energy from maximally localized Wannier functions, as proposed by P. L. Silvestrelli, also known as vdWWF1 method [Silvestrelli2008]. For details on this implementation please check [Espejo2012]. The improvements introduced by Andrinopoulos et al. [Andrinopoulos2011], namely the amalgamation procedure, splitting of plike MLWFs into two slike Wannier functions and fractional occupation of MLWFs are performed automatically.
 11: evaluate the vdW correlation energy from maximally localized Wannier functions, as proposed by A. Ambrosetti and P. L. Silvestrelli, also known as vdWWF2 method [Ambrosetti2012].
 14: apply DFT/vdWQHOWF method as proposed by Silvestrelli, which combines the quantum harmonic oscillatormodel with localized Wannier functions [Silvestrelli2013]. For periodic systems a supercell approach has to be used since vdw_supercell is not enabled in this case.
For vdw_xc = 1 and vdw_xc = 2, the implementation follows the strategy devised in the article of RomanPerez and Soler [Romanperez2009].