TY - JOUR
T1 - Six-dimensional quantum calculations of vibration-rotation-tunneling levels of v1 and v2 HCl-stretching excited (HCl)2
AU - Qiu, Yanhui
AU - Zhang, John Z.H.
AU - Bačić, Zlatko
PY - 1998/3/22
Y1 - 1998/3/22
N2 - Results of the first full-dimensional (6D) quantum calculations of the vibrational levels of the v1 and v2 HCl-stretch excited (HCl)2, for total angular momentum J = 0, are presented. Three 6D potential energy surfaces (PESs) were employed. Two widely used PESs, the ab initio PES of Bunker and co-workers and the semiempirical PES by Elrod and Saykally, are found to give negligible tunneling splittings (≤5 × 10-2 cm-1) for the vibrational eigenstates of the v1/v2 excited (HCl)2, in sharp disagreement with the experimental tunneling splittings in the v1 and v2 fundamentals, -3.32 and 3.18 cm-1. In an effort to overcome this problem, a 6D electrostatic interaction potential is constructed and added to the ES1 PES; the resulting 6D PES is denoted ES1-EL. Quantum 6D calculations on the ES1-EL PES yield greatly improved tunneling splittings for v1 (-2.31 cm-1) and v2 (2.45 cm-1), which are 70% and 77%, respectively, of the corresponding experimental values. The v1 and v2 fundamental HCl-stretching frequencies calculated on the ES1-EL PES are only 5.9 cm-1 lower and 2.9 cm-1 higher, respectively, than their experimental counterparts. In addition, the quantum 6D calculations on the ES1-EL PES provide a comprehensive characterization of the v1/v2 supported vibrational eigenstates of (HCl)2, including their energies, assignments, and tunneling splittings. The vibration-rotation-tunneling dynamics of (HCl)2 in the v1 and v2 excited states which emerged from our calculations differs substantially from that observed for the HF-stretch excited (HF)2.
AB - Results of the first full-dimensional (6D) quantum calculations of the vibrational levels of the v1 and v2 HCl-stretch excited (HCl)2, for total angular momentum J = 0, are presented. Three 6D potential energy surfaces (PESs) were employed. Two widely used PESs, the ab initio PES of Bunker and co-workers and the semiempirical PES by Elrod and Saykally, are found to give negligible tunneling splittings (≤5 × 10-2 cm-1) for the vibrational eigenstates of the v1/v2 excited (HCl)2, in sharp disagreement with the experimental tunneling splittings in the v1 and v2 fundamentals, -3.32 and 3.18 cm-1. In an effort to overcome this problem, a 6D electrostatic interaction potential is constructed and added to the ES1 PES; the resulting 6D PES is denoted ES1-EL. Quantum 6D calculations on the ES1-EL PES yield greatly improved tunneling splittings for v1 (-2.31 cm-1) and v2 (2.45 cm-1), which are 70% and 77%, respectively, of the corresponding experimental values. The v1 and v2 fundamental HCl-stretching frequencies calculated on the ES1-EL PES are only 5.9 cm-1 lower and 2.9 cm-1 higher, respectively, than their experimental counterparts. In addition, the quantum 6D calculations on the ES1-EL PES provide a comprehensive characterization of the v1/v2 supported vibrational eigenstates of (HCl)2, including their energies, assignments, and tunneling splittings. The vibration-rotation-tunneling dynamics of (HCl)2 in the v1 and v2 excited states which emerged from our calculations differs substantially from that observed for the HF-stretch excited (HF)2.
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U2 - 10.1063/1.475891
DO - 10.1063/1.475891
M3 - Article
AN - SCOPUS:0032028872
SN - 0021-9606
VL - 108
SP - 4804
EP - 4816
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 12
ER -