# Weak phonon-mediated pairing in BiS$_2$ superconductor from first principles

## TL;DR

This study uses first-principles calculations to investigate the electron-phonon pairing mechanism in LaO$_{0.5}$F$_{0.5}$BiS$_2$, concluding that phonons alone cannot account for its high superconducting transition temperature.

## Contribution

The paper provides a more accurate calculation of electron-phonon coupling in BiS$_2$ superconductors, challenging previous assumptions about phonon-mediated pairing.

## Key findings

- Charge density wave instability confirmed
- Electron-phonon coupling strength is lower than previous estimates
- Phonon-mediated pairing cannot explain high T_c in this material

## Abstract

Superconductivity in novel bismuth-sulphur superconductors has attracted large research efforts, both experimental and theoretical, but a consensus on the nature of superconductivity in these materials has yet to be reached. Using density functional theory for superconductors, we study the electron-phonon pairing mechanism in LaO$_{0.5}$F$_{0.5}$BiS$_2$. We first confirm the presence of a commensurate charge density wave instability, in accordance with previous studies. Using a recently developed integration scheme for the electron-phonon coupling, we found that its strength is much lower than previously calculated, due to improved density of state calculations. We finally conclude that conventional phonon-mediated pairing cannot explain the high superconducting transition temperatures observed in this material.