Nonlinear optical responses of crystalline systems: Results from a velocity gauge analysis

TL;DR

This paper discusses a method for calculating nonlinear optical responses in crystalline systems using the velocity gauge, addressing computational challenges and demonstrating its application to monolayer graphene.

Contribution

It introduces a systematic approach for perturbative calculations of nonlinear optical responses in the velocity gauge for any band model.

Findings

Successful numerical calculation of nonlinear response in monolayer graphene

Highlights advantages of velocity gauge in nonlinear optical calculations

Addresses relaxation parameter inclusion in the model

Abstract

In this work, the difficulties inherent to perturbative calculations in the velocity gauge are addressed. In particular, it is shown how calculations of nonlinear optical responses in the independent particle approximation can be done to any order and for any finite band model. The procedure and advantages of the velocity gauge in such calculations are described. The addition of a phenomenological relaxation parameter is also discussed. As an illustration, the nonlinear optical response of monolayer graphene is numerically calculated using the velocity gauge.