Calculation of the specific heat of optimally K-doped BaFe$_2$As$_2$

TL;DR

This study uses density functional theory to calculate the specific heat of optimally K-doped BaFe$_2$As$_2$, finding initial discrepancies with experimental data that are improved by potential adjustments, revealing insights into electron-phonon interactions.

Contribution

The paper introduces a correction to the potential on iron atoms in DFT calculations, significantly improving the accuracy of heat capacity and related properties for K-doped BaFe$_2$As$_2$.

Findings

Initial DFT calculations underestimate specific heat by a factor of five.

Adjusting the iron potential enhances heat capacity and other properties.

Electron-phonon coupling is strongly increased after correction.

Abstract

The calculated specific heat of optimally K-doped BaFe$_2$As$_2$ in density functional theory is about five times smaller than that found in the experiment. We report that by adjusting the potential on the iron atom to be slightly more repulsive for electrons improves the calculated heat capacity as well as the structural, magnetic, and electronic properties of Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$. Applying the same correction to the antiferromagnetic state, we find that the electron-phonon coupling is strongly enhanced.