Fast quasi-centroid molecular dynamics

We describe a fast implementation of the quasi-centroid molecular dynamics (QCMD) method in which the quasi-centroid potential of mean force is approximated as a separable correction to the classical interaction potential. This correction is obtained by first calculating quasi-centroid radial and angular distribution functions in a short path integral molecular dynamics simulation and then using iterative Boltzmann inversion to obtain an effective classical potential that reproduces these distribution functions in a classical NVT simulation. We illustrate this approach with example applications to the vibrational spectra of gas phase molecules, obtaining excellent agreement with QCMD reference calculations for water and ammonia and good agreement with the quantum mechanical vibrational spectrum of methane.

Automated summary

This paper introduces a fast implementation of the quasi-centroid molecular dynamics method, where an effective classical potential is obtained using iterative Boltzmann inversion to reproduce the radial and angular distribution functions of molecules in a classical NVT simulation. Through applications to vibrational spectra of gas phase molecules, the results show excellent agreement with QCMD reference calculations and good agreement with the quantum mechanical vibrational spectrum.