### Abstract

We have calculated variationally highly excited vibrational (J = 0) levels of the water molecule up to ∼ 27 000 cm^{-1} (relative to the minimum of the potential surface), for a global Sorbie-Murrell-type potential surface. The calculation has been performed in Radau coordinates, using the recently developed DVR-DGB variational approach [Z. Bačić and J. C. Light, J. Chem. Phys. 85, 4594 (1986); 86, 3065 (1987)]. 110 symmetric and 77 antisymmetric vibrational levels have been determined accurately, requiring diagonalization of relatively small Hamiltonian matrices of dimension ∼600. Many of the calculated levels correspond to large amplitude bending vibrations. Nearest neighbor level spacing statistics for the calculated levels above 18 000-20 000 cm^{-1} conform closely to a Wigner distribution, suggesting classically chaotic behavior in this energy range. Convergence rates of these variational calculations for H_{2}O are comparable to those seen earlier for LiCN/LiNC and HCN/HNC. The DVR-based vibrationally adiabatic approach introduced by Light and Bačić [J. Chem. Phys. 87, 4008 (1987)] has also been tested here. Perturbative inclusion of the nonadiabatic corrections has allowed reliable identification of vibrational (J = 0) levels of H _{2}O up to 18 000-20 000 cm^{-1}. With this model potential energy surface, reasonable agreement (∼1%) is obtained with experimentally known vibrational states to ∼20 000 cm^{-1}.

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

Pages (from-to) | 947-955 |

Number of pages | 9 |

Journal | The Journal of chemical physics |

Volume | 89 |

Issue number | 2 |

State | Published - 1988 |

### Fingerprint

### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

*The Journal of chemical physics*,

*89*(2), 947-955.

**A variational localized representation calculation of the vibrational levels of the water molecule up to 27 000 cm-1
.** / Bacic, Zlatko; Watt, D.; Light, J. C.

Research output: Contribution to journal › Article

*The Journal of chemical physics*, vol. 89, no. 2, pp. 947-955.

}

TY - JOUR

T1 - A variational localized representation calculation of the vibrational levels of the water molecule up to 27 000 cm-1

AU - Bacic, Zlatko

AU - Watt, D.

AU - Light, J. C.

PY - 1988

Y1 - 1988

N2 - We have calculated variationally highly excited vibrational (J = 0) levels of the water molecule up to ∼ 27 000 cm-1 (relative to the minimum of the potential surface), for a global Sorbie-Murrell-type potential surface. The calculation has been performed in Radau coordinates, using the recently developed DVR-DGB variational approach [Z. Bačić and J. C. Light, J. Chem. Phys. 85, 4594 (1986); 86, 3065 (1987)]. 110 symmetric and 77 antisymmetric vibrational levels have been determined accurately, requiring diagonalization of relatively small Hamiltonian matrices of dimension ∼600. Many of the calculated levels correspond to large amplitude bending vibrations. Nearest neighbor level spacing statistics for the calculated levels above 18 000-20 000 cm-1 conform closely to a Wigner distribution, suggesting classically chaotic behavior in this energy range. Convergence rates of these variational calculations for H2O are comparable to those seen earlier for LiCN/LiNC and HCN/HNC. The DVR-based vibrationally adiabatic approach introduced by Light and Bačić [J. Chem. Phys. 87, 4008 (1987)] has also been tested here. Perturbative inclusion of the nonadiabatic corrections has allowed reliable identification of vibrational (J = 0) levels of H 2O up to 18 000-20 000 cm-1. With this model potential energy surface, reasonable agreement (∼1%) is obtained with experimentally known vibrational states to ∼20 000 cm-1.

AB - We have calculated variationally highly excited vibrational (J = 0) levels of the water molecule up to ∼ 27 000 cm-1 (relative to the minimum of the potential surface), for a global Sorbie-Murrell-type potential surface. The calculation has been performed in Radau coordinates, using the recently developed DVR-DGB variational approach [Z. Bačić and J. C. Light, J. Chem. Phys. 85, 4594 (1986); 86, 3065 (1987)]. 110 symmetric and 77 antisymmetric vibrational levels have been determined accurately, requiring diagonalization of relatively small Hamiltonian matrices of dimension ∼600. Many of the calculated levels correspond to large amplitude bending vibrations. Nearest neighbor level spacing statistics for the calculated levels above 18 000-20 000 cm-1 conform closely to a Wigner distribution, suggesting classically chaotic behavior in this energy range. Convergence rates of these variational calculations for H2O are comparable to those seen earlier for LiCN/LiNC and HCN/HNC. The DVR-based vibrationally adiabatic approach introduced by Light and Bačić [J. Chem. Phys. 87, 4008 (1987)] has also been tested here. Perturbative inclusion of the nonadiabatic corrections has allowed reliable identification of vibrational (J = 0) levels of H 2O up to 18 000-20 000 cm-1. With this model potential energy surface, reasonable agreement (∼1%) is obtained with experimentally known vibrational states to ∼20 000 cm-1.

UR - http://www.scopus.com/inward/record.url?scp=0000604026&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0000604026&partnerID=8YFLogxK

M3 - Article

VL - 89

SP - 947

EP - 955

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 2

ER -