title: Raman Vibrational Shifts of Small Clusters of Hydrogen Isotopologues.
abstract: Raman vibrational shifts of small parahydrogen (pH2), orthodeuterium (oD2), and paratritium (pT2) clusters with respect to the free molecules are calculated by combining a first order perturbation theory approach with Langevin equation Path Integral Ground State (LePIGS) simulations [ J. Phys. Chem. A 2013 , 117 , 7461 ]. Our theoretical predictions are compared to existing cryogenic free jet expansion results for pure (pH2)N clusters [ Phys. Rev. Lett. 2004 , 92 , 223401 ] and to new measurements for (oD2)N clusters reported here. This method has been successfully used before to predict the Raman vibrational shifts of (pH2)N clusters [ J. Chem. Phys. 2014 , 141 , 014310 ]. The 6-D interaction potential of Hinde [ J. Chem. Phys. 2008 , 128 , 154308 ] is reduced to 1-D using the Adiabatic Hindered Rotor approximation to yield effective pair potentials for both molecules being in the ground vibrational state, and for one of them carrying one quantum of vibrational excitation. These reduced 1-D potentials are fitted to a Morse Long Range analytic form for later convenience. Good agreement between experiment and theory is found for the smaller clusters, but significant deviations remain for the larger ones.
authors.affiliation: Department of Chemistry, University of Waterloo , Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Matthew
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: Laboratory of Molecular Fluid Dynamics, Instituto de Estructura de la Materia, CSIC , Serrano 121, E-28006 Madrid, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Fernández
authors.affiliation: Department of Chemistry, University of Waterloo , Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Nabil
authors.initials: N
authors.lastname: Faruk
authors.affiliation: Department of Chemistry, University of Waterloo , Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Marcel
authors.initials: M
authors.lastname: Nooijen
authors.affiliation: Department of Chemistry, University of Waterloo , Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Le Roy
authors.affiliation: Laboratory of Molecular Fluid Dynamics, Instituto de Estructura de la Materia, CSIC , Serrano 121, E-28006 Madrid, Spain.
authors.forename: Juan H
authors.initials: JH
authors.lastname: Morilla
authors.affiliation: Laboratory of Molecular Fluid Dynamics, Instituto de Estructura de la Materia, CSIC , Serrano 121, E-28006 Madrid, Spain.
authors.forename: Guzmán
authors.initials: G
authors.lastname: Tejeda
authors.affiliation: Laboratory of Molecular Fluid Dynamics, Instituto de Estructura de la Materia, CSIC , Serrano 121, E-28006 Madrid, Spain.
authors.forename: Salvador
authors.initials: S
authors.lastname: Montero
authors.affiliation: Department of Chemistry, University of Waterloo , Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Pierre-Nicholas
authors.initials: PN
authors.lastname: Roy