Ab initio centroid path integral molecular dynamics:application to vibrational dynamics of diatomic molecular systems

摘要

An ab initio centroid molecular dynamics (CMD) method is developed by combining the CMD method with the ab initio molecular orbital method.The ab initio CMD method is applied to vibrational dynamics of diatomic molecules,H_2 and HF.For the H_2 molecule,the temperature dependence of the peak frequency of the vibrational spectral density is investigated.The results are compared with those obtained by the ab initio classical molecular dynamics method and exact quantum mechanical treatment.It is shown that the vibrational frequency obtained from the ab initio CMD approache the exact first exciation frequency as the temperature lowers.For the HF molecule,the position autocorrelation function is also analyzed in detail.The present CMD method is shown to well reproduce the exact quantum result for the information on the vibrational properties of the system.