Volume 221, 2020

Which quantum statistics–classical dynamics method is best for water?

Abstract

There are a variety of methods for including nuclear quantum effects in dynamics simulations by combining quantum Boltzmann statistics with classical dynamics. Among them are thermostatted ring-polymer molecular dynamics (TRPMD), centroid molecular dynamics (CMD), quasi-centroid molecular dynamics (QCMD), and the linearised semi-classical initial value representation (LSC-IVR). Here we make a systematic comparison of these methods by calculating the infrared spectrum of water in the gas phase, and in the liquid and ice phases (using the q-TIP4P/F model potential). Some of these results are taken from previous work, and some of them are new (including the LSC-IVR calculations for ice, and extensions of all the spectra into the near-infrared region dominated by overtone and combination bands). Our results suggest that QCMD is the best method for reproducing fundamental transitions in the spectrum, and that LSC-IVR gives the best overall description of the spectrum (albeit with large errors in the bend fundamental band caused by zero-point-energy leakage). The TRPMD method gives damped spectra that line up with the QCMD spectra, and is by far the cheapest method.

Graphical abstract: Which quantum statistics–classical dynamics method is best for water?

Associated articles

Article information

Article type
Paper
Submitted
03 Jun 2019
Accepted
14 Jun 2019
First published
15 Jun 2019

Faraday Discuss., 2020,221, 350-366

Which quantum statistics–classical dynamics method is best for water?

R. L. Benson, G. Trenins and S. C. Althorpe, Faraday Discuss., 2020, 221, 350 DOI: 10.1039/C9FD00077A

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