First-principles prediction of the Raman shifts in parahydrogen clusters

Nabil Faruk; Matthew Schmidt; Hui Li; Robert J Le Roy; Pierre-Nicholas Roy

doi:10.1063/1.4885275

First-principles prediction of the Raman shifts in parahydrogen clusters

J Chem Phys. 2014 Jul 7;141(1):014310. doi: 10.1063/1.4885275.

Authors

Nabil Faruk¹, Matthew Schmidt¹, Hui Li¹, Robert J Le Roy¹, Pierre-Nicholas Roy¹

Affiliation

¹ Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.

PMID: 25005292
DOI: 10.1063/1.4885275

Abstract

We report a first-principles prediction of the Raman shifts of parahydrogen (pH2) clusters of sizes N = 4-19 and 33, based on path integral ground-state simulations with an ab initio potential energy surface. The Raman shifts are calculated, using perturbation theory, as the average of the difference-potential energy surface between the potential energy surfaces for vibrationally excited and ground-state parahydrogen monomers. The radial distribution of the clusters is used as a weight function in this average. Very good overall agreement with experiment [G. Tejeda, J. M. Fernández, S. Montero, D. Blume, and J. P. Toennies, Phys. Rev. Lett. 92, 223401 (2004)] is achieved for p(H2)(2-8,13,33). A number of different pair potentials are employed for the calculation of the radial distribution functions. We find that the Raman shifts are sensitive to slight variations in the radial distribution functions.