Simulated structure, dynamics and vibrational spectra of liquid benzene

A classical molecular dynamics simulation of liquid benzene is performed, using a potential model which allows for full molecular flexibility. The short range intermolecular radial distribution function is on average reminiscent of the crystalline structure, although practically no preferential orientation can be found for the molecules in the first coordination shell. The average cage lifetime and its vibrational dynamics are obtained from appropriate time correlation functions. The intramolecular vibrations are investigated by calculating the vibrational density of states and the infrared and Raman spectra, achieving an excellent agreement with the experimental data. Finally, the dephasing of the nu (1)(A(1g)) ring breathing mode and of the nu (6)(E-2g) in-plane bending mode is analyzed on the basis of the Kubo dephasing function. For nu (1) mode the Kubo correlation time of 516 fs agrees with the experimental value, and is consistent with a relaxation mechanism involving the cage reorganization. In contrast, nu (6) has a practically pure Lorentzian line shape, with a width of 7.16 cm(-1) in perfect agreement with the experimental value of 7.2 cm(-1).