# Spin-polarised systems and spin-orbit coupling

### This page gives hints on how to set parameters for a spin-polarized calculation with the ABINIT package.

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

Mentioned in help_features#2.2.

### Table of content:

- 1. Introduction.
- 2. Related lesson(s) of the tutorial.
- 3. Related input variables.
- 4. Selected input files.

### 1. Introduction.

The electronic system may be computed in the spin-unpolarized or spin-polarized case, with the possibility to impose occupation numbers of majority and minority spins, and the spins of the starting configuration. A specific option for efficient treatment of anti-ferromagnetism (Shubnikov groups) is available. The treatment of non-collinear magnetism is available (some details of the implementation can de found here). The total magnetic moment of the unit cell can be constrained. The local magnetization can also be constrained.
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### 2. Related lesson(s) of the tutorial.

- The lesson on spin in ABINIT presents the properties related to spin: spin-polarized calculations and spin-orbit coupling.
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### 3. Related input variables.

Basic input variables:

... nspden [Number of SPin-DENsity components]
... nspinor [Number of SPINORial components of the wavefunctions]
... nsppol [Number of SPin POLarization]
... spinat [SPIN for AToms]

Useful input variables:

... diemixmag [model DIElectric MIXing factor for the MAGgnetization]
... genafm [GENerator of the translation for Anti-FerroMagnetic space group]
... pawspnorb [PAW - option for SPiN-ORBit coupling]
... so_psp [Spin-Orbit treatment for each PSeudoPotential]
... spgroupma [SPace GROUP number defining a MAgnetic space group]
... spinmagntarget [SPIN-MAGNetization TARGET]
... spnorbscl [SPin-ORBit SCaLing]
... symafm [SYMmetries, Anti-FerroMagnetic characteristics]

Relevant internal variables:

... %ptgroupma [PoinT GROUP number for the MAgnetic space group]
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### 4. 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/v1/Input: t21.in t39.in

tests/v2/Input: t74.in t75.in

tests/v3/Input: t22.in t23.in t51.in

tests/v5/Input: t16.in t17.in t51.in

tests/v7/Input: t05.in t06.in t07.in
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