# Interface tool from Wannier90 to RESPACK: wan2respack

## TL;DR

The paper introduces 'wan2respack', an interface tool that converts Wannier functions from Wannier90 into a format compatible with RESPACK, enabling accurate derivation of low-energy Hamiltonians for correlated materials.

## Contribution

We developed and validated 'wan2respack', a tool that bridges Wannier90 and RESPACK, facilitating the calculation of low-energy Hamiltonians with consistent Wannier functions.

## Key findings

- 'wan2respack' accurately converts Wannier functions between formats.
- The low-energy Hamiltonians from both Wannier90 and RESPACK formats agree.
- The tool simplifies workflows for correlated material simulations.

## Abstract

We develop the interface tool $\verb|wan2respack|$, which connects $\verb|RESPACK|$ (software that derives the low-energy effective Hamiltonians of solids) with $\verb|Wannier90|$ (software that constructs Wannier functions). $\verb|wan2respack|$ converts the Wannier functions obtained by $\verb|Wannier90|$ into those used in $\verb|RESPACK|$, which is then used to derive the low-energy effective Hamiltonians of solids. In this paper, we explain the basic usage of $\verb|wan2respack|$ and show its application to standard compounds of correlated materials, namely, the correlated metal SrVO$_3$ and the high-$T_{c}$ superconductor La$_2$CuO$_4$. Furthermore, we compare the low-energy effective Hamiltonians of these compounds using Wannier functions obtained by $\verb|Wannier90|$ and those obtained by $\verb|RESPACK|$. We confirm that both types of Wannier functions give the same Hamiltonians. This benchmark comparison demonstrates that $\verb|wan2respack|$ correctly converts Wannier functions in the $\verb|Wannier90|$ format into those in the $\verb|RESPACK|$ format.