Physically-based optical property models of solids are a convenient means of representing the complex index of refraction as a function of frequency and temperature. This modeling approach is especially convenient considering the wide spread use of personal computers and the uncomplicated mathematical form of the models. Models provide a convenient method of cataloging measurements and interpolated between measurements. Several useful models covering absorption and scattering phenomena are presented. Together, these models allow prediction of optical properties over the spectral range from microwaves to the electronic band gap. Temperature dependence of the optical properties cover a more restricted range, but some models predict optical properties from liquid helium to melting temperatures. We have developed an optical properties code incorporating the following models: the classical (one- phonon) oscillator model, our multi-phonon model, the Urbach tail and weak absorption tail models, free-carrier model, and an empirical scatter model. These models require measured parameters which are given for common materials. Comparisons of model calculations of the refractive index, the absorption coefficient, and scattering coefficient to experimental data are presented.