Evaluation of Born and local effective charges in unoriented materials from vibrational spectra

TL;DR

This paper discusses methods to quantify microscopic charges in unoriented materials using vibrational spectra, applying the Lorentz model and analyzing layered transition metal dichalcogenides.

Contribution

It introduces a formalism combining Lorentz model fits and Kramers Kronig analysis for charge quantification in powdered materials.

Findings

Effective techniques for charge analysis in unoriented samples

Application to layered transition metal dichalcogenides and nanoscale analogs

Discussion of conditions for method applicability

Abstract

We present an application of the Lorentz model in which fits to vibrational spectra or a Kramers Kronig analysis are employed along with several useful formalisms to quantify microscopic charge in unoriented (powdered) materials. The conditions under which these techniques can be employed are discussed, and we analyze the vibrational response of a layered transition metal dichalcogenide and its nanoscale analog to illustrate the utility of this approach.