# Basic electronic properties of iron selenide under variation of structural parameters

## TL;DR

This study uses ab initio calculations to explore how varying structural parameters in iron selenide affects its electronic properties and superconducting potential, revealing new tuning methods for transition temperatures.

## Contribution

It provides a detailed analysis of the electronic structure dependence on structural parameters and proposes two novel ways to enhance superconductivity in iron selenide.

## Key findings

- Electronic susceptibility varies nontrivially with structural changes.
- Symmetry of electron pairing is sensitive to lattice modifications.
- Two promising methods to tune superconducting temperatures are identified.

## Abstract

Since the discovery of high-temperature superconductivity in the thin-film FeSe/SrTiO$_3$ system, iron selenide and its derivates have been intensively scrutinized. Using ab initio density functional theory calculations we review the electronic structures that could be realized in iron-selenide if the structural parameters could be tuned at liberty. We calculate the momentum-dependence of the susceptibility and investigate the symmetry of electron pairing within the random phase approximation. Both the susceptibility and the symmetry of electron pairing depend on the structural parameters in a nontrivial way. These results are consistent with the known experimental behavior of binary iron chalcogenides and, at the same time, reveal two promising new ways of tuning superconducting transition temperatures in these materials. On the one hand by expanding the iron lattice of FeSe at constant iron-selenium distance and, on the other hand, by increasing the iron-selenium distance with unchanged iron lattice.