On the applicability of centroid and ring polymer path integral moleculardynamics for vibrational spectroscopy

摘要

Centroid molecular dynamics (CMD) and ring polymer molecular dynamics (RPMD) are twoconceptually distinct extensions of path integral molecular dynamics that are able to generateapproximate quantum dynamics of complex molecular systems. Both methods can be used tocompute quasiclassical time correlation functions which have direct application in molecularspectroscopy; in particular, to infrared spectroscopy via dipole autocorrelation functions. Theperformance of both methods for computing vibrational spectra of several simple but representativemolecular model systems is investigated systematically as a function of temperature and isotopicsubstitution. In this context both CMD and RPMD feature intrinsic problems which are quantifiedand investigated in detail. Based on the obtained results guidelines for using CMD and RPMD tocompute infrared spectra of molecular systems are provided.