TY - JOUR

T1 - An ab initio calculation of the intramolecular stretching spectra for the HF dimer and its D-substituted isotopic species

AU - Jensen, Per

AU - Bunker, P. R.

AU - Karpfen, Alfred

AU - Kofranek, Manfred

AU - Lischka, Hans

N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.

PY - 1990

Y1 - 1990

N2 - We have carried out an ab initio calculation of the intramolecular stretching spectra (wave numbers and transition moments) of (HF)2, (DF)2, and HFDF involving υ1, + υ2 ≤ 3, where υ1 and υ2 are the local mode quantum numbers for the two intramolecular (HF or DF) stretches. The ab initio surface used as a basis for these calculations has already been published [M. Kofranek, H. Lischka, and A. Karpfen, Chem. Phys. 121, 137 (1988); P. R. Bunker, P. Jensen, A. Karpfen, M. Kofranek, and H. Lischka, J. Chem. Phys. 92, 7432 (1990)], but in the present work we have extended the 1520 nuclear geometry points previously available with 198 points in order to explore further the variation of the intramolecular stretching energies and the dipole moment along the minimum energy (trans tunneling) path. We compute the intramolecular stretching energies and transition moments by making an adiabatic separation of the intramolecular stretching motion and the other vibrational motions of the molecules, and we use the semirigid bender Hamiltonian to average over the trans-tunneling motion. For HFHF, we obtain the fundamental level corresponding to the "free-H" stretch ν1 at 3925 cm-1 and that corresponding to the "bound-H" stretch ν2 at 3874 cm-1, in very good agreement with the experimental results of 3930.9 and 3868.1 cm-1, respectively [A. S. Pine, W. J. Lafferty, and B. J. Howard, J. Chem. Phys. 81, 2939 (1984)]. For the higher excited states, we obtain the 2ν1 energy level at 7674 cm-1 (7700 ± 20 cm-1), 2ν2 at 7570 cm-1 (7555 ± 15 cm-1), 3ν1 at 11 259 cm-1 (11 260 cm -1),and3v2 at 11 085 cm-1 (11 060 cm-1), where the experimental values [K. von Puttkamer and M. Quack, Chem. Phys. 139, 31 (1989)] are given in parentheses.

AB - We have carried out an ab initio calculation of the intramolecular stretching spectra (wave numbers and transition moments) of (HF)2, (DF)2, and HFDF involving υ1, + υ2 ≤ 3, where υ1 and υ2 are the local mode quantum numbers for the two intramolecular (HF or DF) stretches. The ab initio surface used as a basis for these calculations has already been published [M. Kofranek, H. Lischka, and A. Karpfen, Chem. Phys. 121, 137 (1988); P. R. Bunker, P. Jensen, A. Karpfen, M. Kofranek, and H. Lischka, J. Chem. Phys. 92, 7432 (1990)], but in the present work we have extended the 1520 nuclear geometry points previously available with 198 points in order to explore further the variation of the intramolecular stretching energies and the dipole moment along the minimum energy (trans tunneling) path. We compute the intramolecular stretching energies and transition moments by making an adiabatic separation of the intramolecular stretching motion and the other vibrational motions of the molecules, and we use the semirigid bender Hamiltonian to average over the trans-tunneling motion. For HFHF, we obtain the fundamental level corresponding to the "free-H" stretch ν1 at 3925 cm-1 and that corresponding to the "bound-H" stretch ν2 at 3874 cm-1, in very good agreement with the experimental results of 3930.9 and 3868.1 cm-1, respectively [A. S. Pine, W. J. Lafferty, and B. J. Howard, J. Chem. Phys. 81, 2939 (1984)]. For the higher excited states, we obtain the 2ν1 energy level at 7674 cm-1 (7700 ± 20 cm-1), 2ν2 at 7570 cm-1 (7555 ± 15 cm-1), 3ν1 at 11 259 cm-1 (11 260 cm -1),and3v2 at 11 085 cm-1 (11 060 cm-1), where the experimental values [K. von Puttkamer and M. Quack, Chem. Phys. 139, 31 (1989)] are given in parentheses.

UR - http://www.scopus.com/inward/record.url?scp=0008972086&partnerID=8YFLogxK

U2 - 10.1063/1.458996

DO - 10.1063/1.458996

M3 - Article

AN - SCOPUS:0008972086

VL - 93

SP - 6266

EP - 6280

JO - The Journal of Chemical Physics

JF - The Journal of Chemical Physics

SN - 0021-9606

IS - 9

ER -