ABINIT internal variables:

List and description.

This document describes several important internal variables, to which the user has no direct access through a keyword, but that are derived from the input variables at the time of their processing and used internally. Their value is fixed for a specific dataset. They are present in the dtset array, in addition to the input variables that can be directly addressed by the user.

The new user is advised to read first the new user's guide, before reading the present file. It will be easier to understand the variables listed in the present file with the help of the tutorial.

When the user is sufficiently familiarized with ABINIT, the file ~abinit/doc/users/tuning.txt will be useful; this file provides tips on optimizing the performance of ABINIT. For response-function calculations using ABINIT, please read the response function help file

Copyright (C) 1998-2010 ABINIT group (DCA, XG, RC)
This file is distributed under the terms of the GNU General Public License, see ~abinit/COPYING or http://www.gnu.org/copyleft/gpl.txt .
For the list of contributors, see ~abinit/doc/developers/contributors.txt.
Go to : ABINIT home Page | Suggested acknowledgments | List of input variables | Tutorial home page | Bibliography
Help files : New user's guide | Abinit (main) | Abinit (respfn) | Mrgddb | Anaddb | AIM (Bader) | Cut3D | Optic
Files that describe input variables:
See also the Space group table

Content of the file : alphabetical list of internals.


A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K. kptns  
L.
M. mband   mgfft   mgfftdg   mpw  
N. natpawu   ndynimage   nfft   nfftdg   nelect  
O.
P.
Q. qptn  
R.
S.
T.
U. usepaw   userec  
V.
W.
X.
Y.
Z. ziontypat  



kptns
Mnemonics: K-PoinTs re-Normalized and Shifted
Characteristic: INTERNAL
Variable type: real array kptns(3,nkpt)

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).



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mband
Mnemonics: Maximum number of BANDs
Characteristic: INTERNAL
Variable type: integer

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



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mgfft
Mnemonics: Maximum of nGFFT
Characteristic: INTERNAL
Variable type: integer

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



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mgfftdg
Mnemonics: Maximum of nGFFT for the Double Grid
Characteristic: INTERNAL
Variable type: integer

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



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mpw
Mnemonics: Maximum number of Plane Waves
Characteristic: INTERNAL
Variable type: integer

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.



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natpawu
Mnemonics: Number of AToms on which PAW+U is applied
Characteristic: INTERNAL
Variable type: integer parameter

This internal variable gives the number of atoms on which LDA/GGA+U method is applied.
It is determined by natom, usepawu and lpawu input keywords.



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ndynimage
Mnemonics: Number of DYNamical IMAGEs
Characteristic: INTERNAL
Variable type: integer

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), it case they are not stored on disk (see mkmem), e.g. the wavefunction array (cg), the density array (rho), etc .



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nelect
Mnemonics: Number of ELECTrons
Characteristic: INTERNAL
Variable type: real number

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 charge:
nelect=zion-charge.



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nfft
Mnemonics: Number of FFT points
Characteristic: INTERNAL
Variable type: integer

If space parallelisation is not used, 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, 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.



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nfftdg
Mnemonics: Number of FFT points for the Double Grid
Characteristic: INTERNAL
Variable type: integer

If space parallelisation is not used, 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, 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.



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qptn
Mnemonics: Q-PoinT re-Normalized
Characteristic: INTERNAL
Variable type: real array qptn(3)

Used if nqpt=1. This internal variable is derived from qpt and qptnrm: qptn(1:3)= qpt(1:3)/ qptnrm.



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usepaw
Mnemonics: USE Projector Augmented Waves method
Characteristic: INTERNAL
Variable type: integer parameter
Default set by the pseudopotential files : either PAW (1) or norm-conserving (0).

This variable is determined by the pseudopotentials files. PAW calculations (see PAW variables) 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.



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userec
Mnemonics: USE RECursion
Characteristic: INTERNAL
Variable type: integer parameter
Default is Value is 0

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



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ziontypat
Mnemonics: Z (charge) of the IONs for the different TYPes of AToms
Characteristic:
Variable type: real array ziontypat(ntypat)
Default is value is set by the pseudopotential files.

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



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Goto : ABINIT home Page | Suggested acknowledgments | List of input variables | Tutorial home page | Bibliography
Help files : New user's guide | Abinit (main) | Abinit (respfn) | Mrgddb | Anaddb | AIM (Bader) | Cut3D | Optic