Raman frequencies calculated as functions of temperature and pressure using volume data for solid phase I of benzene

Abstract

Raman frequencies of six lattice modes are calculated as a function of pressure using the volume data from the literatüre by means of the isothermal mode Grüneisen parameter (γT) for the solid phase I of benzene. We find that by determining the γT decreasing, the Raman frequencies calculated for the phonon modes increase with increasing pressure in this solid phase of benzene, which agree with the observed Raman data. We also predict the T-P phase diagram between the solid phases of I and I′ by using the calculated Raman frequencies of the six lattice modes of benzene. Our calculated T-P diagram does not match properly with the observed data, which needs to be reconsidered by analyzing a number of measurements for the I−I′ transition in benzene.Our results indicate that this method of calculating the Raman frequencies from the volume data through the mode Grüneisen parameter and predicting the T-P phase diagram from the calculated Raman frequencies, is adequate and it can also be applied to some other hydrocarbons such as naphthalene and anthracene.