Optimizing the tight-binding parametrization of the quasi-one-dimensional superconductor K2Cr3As3

TL;DR

This paper refines the tight-binding model for the superconductor K2Cr3As3 using DFT and Wannier functions, emphasizing the importance of in-plane hoppings for accurate electronic structure representation.

Contribution

It provides a detailed parametrization of the tight-binding model for K2Cr3As3, highlighting the necessity of including in-plane hoppings to accurately capture its electronic properties.

Findings

Good agreement with DFT for extended hopping sets

In-plane hoppings up to next-nearest neighbors are essential

Accurate Fermi surface and population descriptions achieved

Abstract

We study the tight-binding dispersion of the recently discovered superconductor K2Cr3As3, obtained from Wannier projection of Density Functional Theory (DFT) results. In order to establish quantitatively the actual degree of quasi-one dimensionality of this compound, we analyze the electronic band structure for two reduced sets of hopping parameters: one restricted to the Cr-As tubes and another one retaining a minimal number of in-plane hoppings. The corresponding total and local density of states of the compound are also computed with the aim of assessing the tight-binding results with respect to the DFT ones. We find a quite good agreement with the DFT results for the more extended set of hopping parameters, especially for what concerns the orbitals that dominate at the Fermi level. Accordingly, we conclude that one cannot avoid taking into account in-plane hoppings up to the next-nearest-neighbors cells even only to describe correctly the Fermi surface cuts and the populations along the kz direction. Such a choice of a minimal number of hopping parameters directly reflects in the possibility of correctly describing correlations and magnetic interactions.