# Electronic band structure and related topics

### This page gives hints on how to generate the electronic band structure related topics with the ABINIT package.

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

Mentioned in topic_k-points, help_features#8.

### Table of content:

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

### 1. Introduction.

The eigenenergies along a set of segments can be computed (non-self-consistent calculations iscf=-2) using a negative value of kptopt, with kptbounds defining the end points of the segments, and ndivsm (or ndivk) defining the sampling.

A band structure can even be represented using weights proportional to the orbital content (so-called "Fat Bands"), in case of PAW calculation, see pawfatbnd, and related variables.

Different interpolation schemes for the band energies can be defined thanks to einterp. The Wannier interpolation is also available through the use of the wannier90 post-processor.

The band structure from a supercell calculation can be unfolded to the (large) Brillouin zone of the (small) primitive cell thanks to the fold2bloch post-processor. See the related topic_Unfolding.

Different plotting postprocessors exist to produce graphical representations of electronic band structures from ABINIT. The most powerful is based on Abipy. Simpler tools also exist, and can be found in ~abinit/scripts/post_processing, e.g. AbinitBandStructureMaker.py, plot_bandstructure.py or abinit_eignc_to_bandstructure.py.
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### 2. Related input variables.

Basic input variables:

... iscf [Integer for Self-Consistent-Field cycles]
... kptbounds [K PoinT BOUNDarieS]
... kptopt [KPoinTs OPTion]
... ndivsm [Number of DIVisions for the SMallest segment]

Useful input variables:

... einterp [Electron bands INTERPolation]
... iatsph [Index for the ATomic SPHeres of the atom-projected density-of-states]
... natsph [Number of ATomic SPHeres for the atom-projected density-of-states]
... ndivk [Number of DIVisions of K lines]
... pawfatbnd [PAW: print band structure in the FAT-BaND representation]
... ratsph [Radii of the ATomic SPHere(s)]
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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/v8/Input: t04.in

tests/v5/Input: t20.in

tests/v6/Input: t14.in

tests/v7/Input: t71.in t72.in
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