Effect of nonadiabaticity and disorder on nonlinear optical susceptibilities

Abstract

The effect of nonadiabaticity on optical linear polarizability ({alpha}) and third-order polarizability ({gamma}) is investigated numerically for a Holstein-Hubbard finite chain system. The variations of {alpha} and {gamma} are studied as a function of the nonadiabaticity parameter, electron-phonon coupling strength and electron-electron interactions. For a specific range of values of each of these parameters, {alpha} and {gamma} are significantly enhanced. Disorder in either electronic or phonon degrees of freedom is also found to enhance optical nonlinearity. {copyright} {ital 1999} {ital The American Physical Society}