A molecular dynamics simulation of dephasing in liquid nitrogen

We relate the dephasing of molecular vibrations in liquids to certain correlation functions involving only the translational and rotational degrees of freedom; these correlation functions are then determined through a classical molecular dynamics simulation of rigid, nonvibrating molecules. Using a Lennard-Jones atom–atom potential for N2 (liq) near its boiling point, we calculate a dephasing time of 62 psec, in good agreement with picosecond pulse and isotropic Raman linewidth measurements. The importance and characterisic time scales of different dephasing mechanisms are studied, and the significant effect of vibrational anharmonicity is demonstrated.