First principles calculation of vibrational Raman spectra in large systems: signature of small rings in crystalline SiO2

TL;DR

This paper introduces an efficient first-principles method to calculate vibrational Raman spectra in large periodic systems, enabling detailed analysis of small ring signatures in crystalline SiO2 with minimal additional computational cost.

Contribution

The authors develop a novel approach to compute Raman intensities from density functional theory that significantly reduces computational effort compared to previous methods.

Findings

Successfully applied to various SiO2 polymorphs

Identified Raman signatures of small rings in crystalline structures

Demonstrated efficiency in large system calculations

Abstract

We present an approach for the efficient calculation of vibrational Raman intensities in periodic systems within density functional theory. The Raman intensities are computed from the second order derivative of the electronic density matrix with respect to a uniform electric field. In contrast to previous approaches, the computational effort required by our method for the evaluation of the intensities is negligible compared to that required for the calculation of vibrational frequencies. As a first application, we study the signature of 3- and 4-membered rings in the the Raman spectra of several polymorphs of SiO2, including a zeolite having 102 atoms per unit cell.