The collective dynamical properties of HCl : the transverse current correlations

Results are presented for the transverse current correlation functions and their spectra obtained by molecular dynamics simulation of liquid hydrogen chloride (HCl) at 201 K. To rationalize the results we analyze the data in the framework of the Mori-Zwanig theory and calculate the first order memory functions. This is done both in and exactly from the simulation data and by suitable approximations with one and two decay rates. It is found that the simple viscoelastic approximation with a single relaxation time is not sufficient to describe the dynamics of HCl whereas the extended model with two relaxation-times function accounts quite well for the simulation data in the low wave-number regime. Hydrogen bonding is found to play only a minor role in the dynamics of the liquid and the main features compare well with a simple liquidlike argon. (C) 2001 American Institute of Physics