Numerical models for Rayleigh-Brillouin scattering (RBS) spectra from molecular gases are obtained and discussed in this paper. The current publicly-available S6 model is for polarized RBS spectra only, despite the existence of both polarized and depolarized RBS light in many real applications. One of the new models (Q9) can be used to calculate both polarized and depolarized RBS spectra. In addition, this model has a solid physical ground because it is based on the correct Waldmann-Snider equation in which molecular internal energy is treated quantum-mechanically.