# ABINIT Wannier90 interface input variables:

## List and description.

This document lists and provides the description of the name (keywords) of parallelisation input variables to be used in the main input file of the abinis code.

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

When the user is sufficiently familiarized with ABINIT, the reading of the ~abinit/doc/users/tuning file might be useful. For response-function calculations using abinis, please read the response function help file

##### Copyright (C) 1998-2009 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 initials of contributors, see ~abinit/doc/developers/contributors.txt .

Goto : ABINIT home Page | Suggested acknowledgments | List of input variables | Tutorial home page | Bibliography

Help files : New user's guide | Abinis (main) | Abinis (respfn) | Mrgddb | Anaddb | AIM (Bader) | Cut3D | Optic | Mrgscr

Files that describe other input variables:

- Basic variables, VARBAS
- Developper variables, VARDEV
- File handling variables, VARFIL
- Geometry builder + symmetry related variables, VARGEO
- Ground-state calculation variables, VARGS
- GW variables, VARGW
- Internal variables, VARINT
- Projector-Augmented Wave variables, VARPAW
- Response Function variables, VARRF
- Structural optimization variables, VARRLX

### Content of the file : alphabetical list of variables.

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W. w90iniprj w90prtunk
X.
Y.
Z.
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w90iniprj
Mnemonics: Wannier90- INItial PROJections
Characteristic:
Variable type: integer
Default is 1 (random projections).
In order to find the Maximally Localized Wannier Functions, the user has to provide an initial guess. A set of localized trial orbitals is chosen corresponding to some rough initial guess at the Wannier Functions, and these are projected onto the Bloch eigenstates. See Ivo Souza, Nicola Marzari, and David Vanderbilt. Phys. Rev. B, 65, 035109 (2001).
These initial projections are stored in a file .amn and the variable w90iniprj is used to construct them:

- w90iniprj=1: Random projections.
- w90iniprj=2: Projections based on prj. (Not yet in use)
- w90iniprj=3: Projections based on phi. (Not yet in use)
- w90iniprj=4: The initial projections will be a linear combination of hydrogenic atomic orbitals.
  The user has to define the projections in the secondary input file wannier90.win
  Information about how to define them can be found in the manual of Wannier90. See www.wannier.org

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w90prtunk
Mnemonics: Wannier90- PRINT UNKp.s file
Characteristic:
Variable type: integer
Default is set to zero.
Defines whether or not the UNKp.s file will be printed.

- w90prtunk=0: Do not print the UNKp.s files
- w90prtunk=1: Print the UNKp.s files on a fine grid
- w90prtunk>1: Print the UNKp.s files on a coarse grid
  Instead of printing every record we will print every w90prtunk records. This is useful to reduce the size of the UNKp.s files, but, the quality is also reduced.

The default is set to zero because UNKp.s files occupy a lot of memory. These files contain the periodic part of the bloch states represented on a regular real space grid. They are indexed by k-point p (from 1 to nkpt) and spin s ('1' for 'up','2' for 'down').
The name of the wavefunction file is assumed to have the form:
write(wfnname,200) p, spin
200 format ('UNK',i5.5,'.',i1)
These file are unformatted. The first line of each file contains 5 integers: the number of grid points in each direction (n1, n2 and n3), the k-point number ikpt and the total number of bands mband in the file. The following rows contain the wavefunctions in real space.

These files are written in the following way for the coarse grid:

    write(iun_plot) n1/w90prtunk,n2/w90prtunk,n3/w90prtunk,ikpt,nband
    write(iun_plot) (((fofr(1,jj1,jj2,jj3),fofr(2,jj1,jj2,jj3),&
    &      jj1=1,n1,w90prtunk),jj2=1,n2,w90prtunk),jj3=1,n3,w90prtunk)

Where fofr is a double precision variable which contains the wavefunctions in real space. Note that in order to reduce the size of the UNK files we are just including records in the wavefunctions for 1/(w90prtunk^3) of the grid points. That is why we divide n1, n2 and n3 by prtunk. The output .xsf files for plotting with XCrysDen will also be on the coarse grid. When this dosen't produce an acceptable plot, prtunk can be set to 1 to output every grid point. (You should try spline interpolation in XCrysDen first.)
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Goto : ABINIT home Page | Suggested acknowledgments | List of input variables | Tutorial home page | Bibliography

Help files : New user's guide | Abinis (main) | Abinis (respfn) | Mrgddb | Anaddb | AIM (Bader) | Cut3D | Optic | Mrgscr