Modeling the index of refraction of insulating solids with a modified Lorentz oscillator model

A modification of the Lorentz oscillator model for optical constants is proposed in an effort to achieve better agreement with experimental data while keeping the calculation simple. Improvement in agreement between theoretical and experimental data obtained with a variable line shape (frequency-dependent damping constant) over a wide spectral range is demonstrated through modeling the index of refraction of Si3N4 (1-24 eV), SiO (0.15-25 eV) and amorphous and crystalline SiO2 (0.15-25 eV). Model parameters are estimated by acceptance-probability-controlled simulated annealing. Excellent agreement between the modified model and the experimental data is obtained for both real and imaginary parts of the index of refraction. (C) 1998 Optical Society of America.