The frequency-resolved frozen phonon multislice method and its application to vibrational EELS using parallel illumination

TL;DR

This paper advances vibrational EELS modeling by refining the frequency-resolved frozen phonon multislice method, demonstrating its effectiveness in accurately simulating phonon spectra in hexagonal boron nitride.

Contribution

It introduces a detailed review and an improved implementation of the method, including a hotspot thermostat, for more accurate vibrational scattering simulations.

Findings

Simulated spectra match theoretical phonon bandstructure

Method accurately captures phonon energies and polarization vectors

Application to hexagonal boron nitride validates the approach

Abstract

We explore the capabilities of the frequency-resolved frozen phonon multislice method introduced in Phys. Rev. Lett. 124, 025501 (2020) to model inelastic vibrational scattering in transmission electron microscopy. We review the method in detail and discuss advantages of using a so called hotspot thermostat instead of the $\delta$-thermostat used in our first report. We apply the method to simulate vibrational electron energy loss spectra of hexagonal boron nitride under plane wave illumination. Simulated spectroscopic information well represents the theoretical phonon bandstructure of the studied material, both in terms of energies as well as polarization vectors of individual phonon modes.