In this paper an attempt is made to study the Einstein relation for the diffusivity-mobility ratio
(DMR) in nonlinear optical compounds on the basis of a newly formulated electron energy
spectrum taking into account the combined influences of the anisotropies in the effective
electron mass and the spin orbit splitting constant together with the inclusion of crystal field
splitting in the Hamiltonian within the framework of kp formalism. The corresponding results
for III–V, ternary and quaternary types of optoelectronic materials form a special case of our …