internal input variables

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

kptns

Mnemonics: K-PoinTs re-Normalized and Shifted
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_k-points
Variable type: real
Dimensions: (3,nkpt)
Default value: None
Added in version: before_v9

If nqpt = 0, or if one is doing a reponse calculation, this internal variable is derived from kpt and kptnrm: kptns (1:3,:)= kpt(1:3,:)/ kptnrm, so that it is kpt renormalized by kptnrm.

If nqpt = 1 and one is not doing a ground-state calculation, this internal variable is derived from kpt, kptnrm and %qptn: kptns (1:3,:)= kpt(1:3,:)/ kptnrm+ %qptn(1:3), so that it is kpt renormalized by kptnrm, then shifted by %qptn(1:3).

kptns_hf

Mnemonics: K-PoinTs re-Normalized and Shifted, for the Hartree-Fock operator
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_k-points
Variable type: real
Dimensions: (3,nkpthf)
Default value: None
Added in version: before_v9

kptns_hf is the subset of the full Brillouin Zone k point grid for wavefunctions, used to build the Fock operator, see fockdownsampling.

mband

Mnemonics: Maximum number of BANDs
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_BandOcc
Variable type: integer
Dimensions: scalar
Default value: None
Added in version: before_v9

This internal variable derives the maximum number of bands over all k-points and spin-polarisation from nband(1:nkpt*nsppol).

mgfft

Mnemonics: Maximum of nGFFT
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_Planewaves
Variable type: integer
Dimensions: scalar
Default value: None
Added in version: before_v9

This internal variable contains the maximum of ngfft(1:3).

mgfftdg

Mnemonics: Maximum of nGFFT for the Double Grid
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_Planewaves
Variable type: integer
Dimensions: scalar
Default value: None
Added in version: before_v9

This internal variable contains the maximum of ngfftdg(1:3).

mpw

Mnemonics: Maximum number of Plane Waves
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_Planewaves
Variable type: integer
Dimensions: scalar
Default value: None
Added in version: before_v9

This internal variable gives the maximum of the number of plane waves over all k-points. It is computed from ecut and the description of the cell, provided by acell, rprim, and/or angdeg.

natpawu

Mnemonics: Number of AToms on which PAW+U is applied
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_DFT+U
Variable type: integer
Dimensions: scalar
Default value: None
Only relevant if: usepawu == 1
Added in version: before_v9

This internal variable gives the number of atoms on which the DFT+U method is applied. This value is determined from lpawu.

ndynimage

Mnemonics: Number of DYNamical IMAGEs
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_PIMD
Variable type: integer
Dimensions: scalar
Default value: None
Added in version: before_v9

This internal variable gives the number of dynamical images, immediately deduced from the number of non-zero values present in dynimage. It is used to dimension many memory-consuming arrays (one copy for each image), e.g. the wavefunction array (cg), the density array (rho), etc.

nelect

Mnemonics: Number of ELECTrons
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_BandOcc
Variable type: real
Dimensions: scalar
Default value: AUTO_FROM_PSP
Added in version: before_v9

This internal variable gives the number of electrons per unit cell, as computed from the sum of the valence electrons related to each atom (given in the pseudopotential, where it is called “zion”), and the input variable cellcharge: nelect = zion-cellcharge.

When there are several images, although cellcharge is an array, nelect is initialized with the first image, namely nelect = zion-cellcharge(1).

nfft

Mnemonics: Number of FFT points
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_Planewaves
Variable type: integer
Dimensions: scalar
Default value: None
Added in version: before_v9

If space parallelization is not used (that is, if paral_kgb == 0), this internal variable gives the number of Fast Fourier Transform points in the grid generated by ngfft(1:3). It is simply the product of the three components of ngfft.

If space parallelisation is used (that is, if paral_kgb == 1), then it becomes the number of Fast Fourier Transform points attributed to the particular processor. It is no longer the above-mentioned simple product, but a number usually close to this product divided by the number of processors on which the space is shared.

nfftdg

Mnemonics: Number of FFT points for the Double Grid
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_Planewaves
Variable type: integer
Dimensions: scalar
Default value: None
Added in version: before_v9

If space parallelisation is not used (that is, if paral_kgb == 0), this internal variable gives the number of Fast Fourier Transform points in the (double) grid generated by ngfftdg(1:3). It is simply the product of the three components of ngfftdg.

If space parallelisation is used (that is, if paral_kgb == 1), then it becomes the number of Fast Fourier Transform points attributed to the particular processor. It is no longer the above-mentioned simple product, but a number usually close to this product divided by the number of processors on which the space is shared.

npweps

Mnemonics: Number of PlaneWaves for EPSilon (the dielectric matrix)
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_Susceptibility
Variable type: integer
Dimensions: scalar
Default value: None
Added in version: before_v9

npweps determines the size of the planewave set used to represent the independent-particle susceptibility \(\chi^{(0)}_{KS}\), the dielectric matrix \(\epsilon\) and its inverse. It is an internal variable, determined from ecuteps.

npwsigx

Mnemonics: Number of PlaneWaves for SIGma eXchange
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_SelfEnergy
Variable type: integer
Dimensions: scalar
Default value: None
Added in version: before_v9

npwsigx determines the cut-off energy of the planewave set used to generate the exchange part of the self-energy operator. It is an internal variable, determined from the largest of ecutsigx or ecutwfn.

npwwfn

Mnemonics: Number of PlaneWaves for WaveFunctioNs
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_Susceptibility, topic_SelfEnergy
Variable type: integer
Dimensions: scalar
Default value: None
Added in version: before_v9

npwwfn is the size of the planewave set used to represent the wavefunctions in the formula that generates the independent-particle susceptibility \(\chi^{(0)}_{KS}\). It is an internal variable, determined from ecutwfn.

qptn

Mnemonics: Q-PoinT re-Normalized
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_DFPT
Variable type: real
Dimensions: (3)
Default value: 3 * 0
Only relevant if: nqpt == 1
Added in version: before_v9

Only used if nqpt = 1.

In ground-state calculation, the vector qptn(1:3) is added to each renormalized k point (whatever the value of kptopt used) to generate the normalized, shifted, set of k-points %kptns(1:3,1: nkpt ). In response-function calculations, qptn(1:3) defines the wavevector of the phonon-type calculation.

qptn(1:3) can be produced on the basis of the different methods described in qptopt, like using qpt(1:3) with renormalisation provided by qptnrm, or using the other possibilities defined by iqpt, ngqpt, nshiftq, qptrlatt, shiftq.

For insulators, there is no restriction on the q-points to be used for the perturbations. By contrast, for metals, for the time being, it is advised to take q points for which the k and k+q grids are the same (when the periodicity in reciprocal space is taken into account). Tests remain to be done to see whether other q points might be allowed (perhaps with some modification of the code).

usefock

Mnemonics: USE FOCK exact exchange
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_Hybrids
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

This internal variable is automatically set to 1 when the value of ixc refers to an Hartree-Fock calculation or hybrid functionals.

• 0 → No use of exact exchange.
• 1 → exact exchange is required for the calculation.

usepaw

Mnemonics: USE Projector Augmented Waves method
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_PAW
Variable type: integer
Dimensions: scalar
Default value: AUTO_FROM_PSP
Added in version: before_v9

This variable is determined by the pseudopotentials files. PAW calculations (see paw1 tutorial) can only be performed with PAW atomic data input files, while pseudopotential calculations are performed in ABINIT with norm-conserving pseudopotential input files. Most functionalities in ABINIT are available with either type of calculation.

userec

Mnemonics: USE RECursion
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_Recursion
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

This internal variable is set to 1 when the recursion method is activated (see tfkinfunc).

xclevel

Mnemonics: eXchange Correlation functional LEVEL
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_xc, topic_TDDFT
Variable type: integer
Dimensions: scalar
Default value: 0
Added in version: before_v9

Automatically determined from the value of ixc.

• 0 → No XC contribution.
• 1 → LDA functional.
• 2 → GGA functional or hybrid functional based on GGA.
• 3 → Functional for TDDFT.

ziontypat

Mnemonics: Z (charge) of the IONs for the different TYPes of AToms
Characteristics: INTERNAL_ONLY
Mentioned in topic(s): topic_AtomTypes, topic_PseudosPAW
Variable type: real
Dimensions: (ntypat)
Default value: AUTO_FROM_PSP
Added in version: before_v9

Charge of the pseudo-ion (defined as the number of valence electrons that are needed to screen exactly the pseudopotential).