# Wannier

This page gives hints on how to perform Wannier functions calculation with the ABINIT package.

## Introduction¶

There are two ways to obtain Wannier functions with ABINIT:

In order to do Wannier interpolation or analysis of hopping integrals, real space Wannier functions can be built using the variables plowan_realspace and plowan_nt as well as plowan_it. Real space Hamiltonian for analysis is given in latex file whose name ending is “wanniereigen” and the band structure is given in the output and log file.

• The second one is to use the external code wannier90 (www.wannier.org) that calculates Maximally Localized Wannier Functions (MLWF). After a ground state calculation the Wannier90 code will obtain the MLWFs requiring just two ingredients:

• The overlaps between the cell periodic part of the Bloch states.

• As a starting guess the projection of the Bloch states onto trial localized orbitals.

What ABINIT do is to take the Bloch functions from a ground state calculation and compute these two ingredients. Then, Wannier90 is run. Wannier90 is included as a library and ABINIT and the process is automatic, so that in a single run you can do both the ground state calculation and the computation of MLWFs. The input variables prtwant, w90iniprj and w90prtunk are related to the use of the wannier90 librairy.

compulsory:

• plowan_bandf Projected Local Orbital WANnier functions BAND Final
• plowan_bandi Projected Local Orbital WANnier functions BAND Initial
• plowan_compute Projected Local Orbital WANnier functions COMPUTATION
• plowan_iatom Projected Local Orbital WANnier functions, Index of ATOM
• plowan_lcalc Projected Local Orbital WANnier functions, L values to use for CALCulation
• plowan_natom Projected Local Orbital WANnier functions, Number of ATOMs
• plowan_nbl Projected Local Orbital WANnier functions, NumBer of L values
• plowan_projcalc Projected Local Orbital WANnier functions, PROJectors values to use for CALCulation
• prtwant PRinT WANT file

basic:

useful:

• plowan_it Projected Local Orbital WANnier functions, Index of Translation.
• plowan_nt Projected Local Orbital WANnier functions, Number of Translation on which the real space values of energy are computed
• plowan_realspace Projected Local Orbital WANnier functions, activate REAL SPACE calculation.

v7:

wannier90: