Calculation of the heat capacity Cp from the temperature-induced and pressure-induced Raman frequency shifts for solid benzene, naphthalene and anthracene

Abstract

The heat capacity Cp is calculated from the temperature-induced and pressure-induced Raman frequency shifts by means of the mode Grüneisen parameter for the I-II transition of solid benzene, naphthalene and anthracene. For this calculation, contributions to Cp are considered due to the six lattice modes of solid benzene, six librational modes of naphthalene and, six phonons and nine vibrons of anthracene with their mode Grüneisen parameters at various temperature (P=0) and pressures (T=300 K). Our calculated Cp explains the observed behavior of the I–II transition in solid benzene and also of naphthalene and anthracene. Temperature dependence of the entropy difference is calculated from the heat capacity for those hydrocarbons, which can be compared with the observed data.Our results indicate that the heat capacity Cp can be calculated as functions of temperature and pressure from the spectroscopic parameters, in particular, the Raman frequency shifts as we have studied here for hydrocarbons.