# ABINIT parallelisation 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) 1998-2006 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 .

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
- Wannier fonctions variables, VARWAN

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

A.
B.
C.
D.
E.
F. fft_opt_lob
G.
H.
I.
J.
K.
L. localrdwf
M.
N. ngroup_rf
O.
P. paral_rf
Q.
R.
S.
T.
U.
V.
W.
X.
Y.
Z.

localrdwf
Mnemonics: LOCAL ReaD WaveFunctions
Characteristic: DEVELOP, PARALLEL
Variable type: integer
Default is 1.
This input variable is used only in abinip. If localrdwf=1, the input wavefunction disk file is read locally by each processor, while if localrdwf=0, only one processor reads it, and BCAST it to other processors.

The option localrdwf=0 is NOT allowed when mkmem==0 (or, for RF, when mkqmem==0, or mk1mem==0), that is, when the wavefunctions are stored on disk. This is still to be coded ...

In the case of a parallel computer with a unique file system, both options are as convenient for the user. However, if the I/O are slow compared to communications between processors, (e.g. for CRAY T3E machines), localrdwf=0 should be much more efficient; if you really need temporary disk storage, switch to localrdwf=1 ).

In the case of a cluster of nodes, with a different file system for each machine, the input wavefunction file must be available on all nodes if localrdwf=1, while it is needed only for the master node if localrdwf=0.

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fft_opt_lob
Mnemonics: Fast Fourier Transform parallelisation - OPTion for LOB algorithm
Characteristic:
Variable type: integer
Default is 0.
Option for LOB algorithm, used in the FFT parallelisation (still in development).

- =1 : old implementation
- =2 : new implementation : parallelization on bands in lobpcgccwf : the calls to getghc are made in sequential on a set of bands (nbdblock) : the aim is to reduce the number of collective communications. This is not yet implemented in lobpcgwf.

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ngroup_rf
Mnemonics: Define the number of groups for parallelization over perturbations
Characteristic: can even be specified separately for each dataset, parameter paral_rf is necessary
Variable type: integer
Default is 0.
This parameter is used in connection to the parallelization over perturbations. It defines the number of groups for distributing the perturbation-cases over the total number of available processors. The maximum number of groups is limited by the number of perturbation cases. The size of each group is again limited by the number k-points.
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paral_rf
Mnemonics: Activate parallelization over perturbations
Characteristic: can even be specified separately for each dataset, parameter ngroup_rf is necessary
Variable type: integer
Default is 0.

This parameter activates the parallelization over perturbations which can be used during RF-Calculation. It is possible to use this type of parallelization in combination to the parallelization over k-points.

Currently total energies calculated by groups, where the master process is not in, are saved in .status_LOGxxxx files.

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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