Correlation Driven Phonon Anomalies in Bulk FeSe

TL;DR

This paper demonstrates that incorporating fluctuating magnetic moments via DFT+eDMFT significantly improves the accuracy of phonon dispersion and density of states predictions in the iron superconductor FeSe, aligning well with experimental data.

Contribution

The study shows that DFT+eDMFT effectively captures magnetic fluctuations, resolving DFT's limitations in modeling lattice dynamics of correlated metallic systems.

Findings

DFT+eDMFT matches experimental phonon data in FeSe

Proper treatment of magnetic fluctuations improves lattice dynamics predictions

Benchmarking eDMFT against experiments aids future material design

Abstract

We study the lattice dynamics of iron superconductor FeSe, and address the fundamental question of how important is proper description of fluctuating magnetic moments in metallic systems for phonon dispersion and phonon density of states. We show that Density Functional Theory (DFT)+ embedded Dynamical Mean-Field Theory (eDMFT) functional approach, which truly captures the fluctuating local moments, largely eliminates the deficiency of DFT for description of lattice dynamics in correlated metallic systems, and predicts phonon dispersion and phonon density of states in very good agreement with available X-ray data and nuclear inelastic scattering. This benchmark between eDMFT and experiment will be important for data science-driven material design, in which DFT is being replaced by beyond DFT methods.