Diffuse Inelastic Neutron Scattering from Anharmonic Vibrations in Cuprite

TL;DR

This study investigates atomic vibrations in cuprite using inelastic neutron scattering and MD simulations, revealing diffuse inelastic intensity caused by anharmonic interactions at high temperatures.

Contribution

It introduces a machine learning-based MD approach to reproduce diffuse inelastic intensity and explains its origin from anharmonic vibrations.

Findings

Diffuse inelastic intensity appears above 300 K.

MD simulations accurately reproduce the diffuse features.

Anharmonic interactions cause phase shifts in vibrations.

Abstract

Atomic vibrational dynamics in cuprite, Cu2O, was studied by inelastic neutron scattering and molecular dynamics (MD) simulations from 10 K to 900 K. Above 300 K, a diffuse inelastic intensity (DII) appeared, obscuring the high-energy phonon modes. Classical MD simulations with a machine learning interatomic potential reproduced general features of the DII, especially with a Langevin thermostat. The DII originates from random phase shifts of vibrating O-atoms that have anharmonic interactions with neighboring Cu-atoms.