# Smart symmetrizer

### This page gives hints on how to use the symetry information to build the system from the irreducible part of the primitive cell with the ABINIT package.

##### Copyright (C) 2016-2017 ABINIT group (FJ)

Mentioned in topic_UnitCell, topic_crystal, help_features#2.1.

### Table of content:

- 1. Introduction.
- 2. Related input variables.
- 3. Selected input files.

### 1. Introduction.

Sometimes, the user knows the space group of the system, the conventional cell vectors, as well as the positions of atoms in the asymmetric (irreducible) part of the cell. From such data, ABINIT can generate the usual primitive cell vectors, as well as the coordinates of all the atoms in this cell.

This is activated if spgroup!=0 and brvltt=-1. The user needs to specify the number of atoms to be read natrd in the asymmetric part of the cell, as well as the expected number of atoms natom in the primitive cell. Some additional information on the axes orientation spgaxor and the cell origin spgorig might also have to be given. See the space group help file.

The specification of a magnetic space group is even possible (antiferromagnetic). See spgroupma and genafm.

See also the topic_UnitCell.
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### 2. Related input variables.

Basic input variables:

... brvltt [BRaVais LaTTice type]
... natom [Number of ATOMs]
... natrd [Number of AToms ReaD]
... spgroup [SPace GROUP number]

Useful input variables:

... chkprim [CHecK whether the cell is PRIMitive]
... genafm [GENerator of the translation for Anti-FerroMagnetic space group]
... spgaxor [SPace Group : AXes ORientation]
... spgorig [SPace Group : ORIGin]
... spgroupma [SPace GROUP number defining a MAgnetic space group]

Relevant internal variables:

... %ptgroupma [PoinT GROUP number for the MAgnetic space group]
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### 3. Selected input files.

WARNING : as of ABINITv8.6.x, the list of input files provided in the specific section of the topics Web pages is still to be reviewed/tuned. In some cases, it will be adequate, and in other cases, it might be incomplete, or perhaps even useless.
The user can find some related example input files in the ABINIT package in the directory /tests, or on the Web:

tests/tutorial/Input: tnuc_1.in

tests/v2/Input: t59.in t60.in

tests/v5/Input: t77.in

tests/v6/Input: t30.in
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