Basis-Independent Spectral Methods for Non-linear Optical Response in Arbitrary Tight-binding Models

Abstract

In this paper, we developed a basis-independent perturbative method for calculating the non-linear optical response of arbitrary non-interacting tight-binding models. Our method is based on the non-equilibrium Keldysh formalism and allows an efficient numerical implementation within the framework of the Kernel Polynomial Method for systems which are not required to be translation-invariant. Some proof-of-concept results of the second-order optical conductivity are presented for the special case of gapped graphene with vacancies and an on-site Anderson disordered potential.