### Abstract

Results of the first full-dimensional (6D) quantum calculations of the vibrational levels of the v_{1} and v_{2} 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 v_{1}/v_{2} excited (HCl)_{2}, in sharp disagreement with the experimental tunneling splittings in the v_{1} and v_{2} 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 v_{1} (-2.31 cm^{-1}) and v_{2} (2.45 cm^{-1}), which are 70% and 77%, respectively, of the corresponding experimental values. The v_{1} and v_{2} 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 v_{1}/v_{2} supported vibrational eigenstates of (HCl)_{2}, including their energies, assignments, and tunneling splittings. The vibration-rotation-tunneling dynamics of (HCl)_{2} in the v_{1} and v_{2} excited states which emerged from our calculations differs substantially from that observed for the HF-stretch excited (HF)_{2}.

Original language | English (US) |
---|---|

Pages (from-to) | 4804-4816 |

Number of pages | 13 |

Journal | Journal of Chemical Physics |

Volume | 108 |

Issue number | 12 |

State | Published - Mar 22 1998 |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

**Six-dimensional quantum calculations of vibration-rotation-tunneling levels of v1 and v2 HCl-stretching excited (HCl)2
.** / Qiu, Yanhui; Zhang, John; Bacic, Zlatko.

Research output: Contribution to journal › Article

*Journal of Chemical Physics*, vol. 108, no. 12, pp. 4804-4816.

}

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

AU - Bacic, 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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M3 - Article

VL - 108

SP - 4804

EP - 4816

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 12

ER -