### Abstract

The high accuracy ab initio adiabatic potential energy surfaces (PESs) of the ground electronic state of the water molecule, determined originally by Polyansky [Science 299, 539 (2003)] and called CVRQD, are extended and carefully characterized and analyzed. The CVRQD potential energy surfaces are obtained from extrapolation to the complete basis set of nearly full configuration interaction valence-only electronic structure computations, augmented by core, relativistic, quantum electrodynamics, and diagonal Born-Oppenheimer corrections. We also report ab initio calculations of several quantities characterizing the CVRQD PESs, including equilibrium and vibrationally averaged (0 K) structures, harmonic and anharmonic force fields, harmonic vibrational frequencies, vibrational fundamentals, and zero-point energies. They can be considered as the best ab initio estimates of these quantities available today. Results of first-principles computations on the rovibrational energy levels of several isotopologues of the water molecule are also presented, based on the CVRQD PESs and the use of variational nuclear motion calculations employing an exact kinetic energy operator given in orthogonal internal coordinates. The variational nuclear motion calculations also include a simplified treatment of nonadiabatic effects. This sophisticated procedure to compute rovibrational energy levels reproduces all the known rovibrational levels of the water isotopologues considered, H2 O16, H2 O17, H2 O18, and D2 O16, to better than 1 cm-1 on average. Finally, prospects for further improvement of the ground-state adiabatic ab initio PESs of water are discussed.

Original language | English |
---|---|

Article number | 204307 |

Journal | The Journal of Chemical Physics |

Volume | 125 |

Issue number | 20 |

DOIs | |

Publication status | Published - 2006 |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

*The Journal of Chemical Physics*,

*125*(20), [204307]. https://doi.org/10.1063/1.2378766

**CVRQD ab initio ground-state adiabatic potential energy surfaces for the water molecule.** / Barletta, Paolo; Shirin, Sergei V.; Zobov, Nikolai F.; Polyansky, Oleg L.; Tennyson, Jonathan; Valeev, Edward F.; Császár, Attila G.

Research output: Contribution to journal › Article

*The Journal of Chemical Physics*, vol. 125, no. 20, 204307. https://doi.org/10.1063/1.2378766

}

TY - JOUR

T1 - CVRQD ab initio ground-state adiabatic potential energy surfaces for the water molecule

AU - Barletta, Paolo

AU - Shirin, Sergei V.

AU - Zobov, Nikolai F.

AU - Polyansky, Oleg L.

AU - Tennyson, Jonathan

AU - Valeev, Edward F.

AU - Császár, Attila G.

PY - 2006

Y1 - 2006

N2 - The high accuracy ab initio adiabatic potential energy surfaces (PESs) of the ground electronic state of the water molecule, determined originally by Polyansky [Science 299, 539 (2003)] and called CVRQD, are extended and carefully characterized and analyzed. The CVRQD potential energy surfaces are obtained from extrapolation to the complete basis set of nearly full configuration interaction valence-only electronic structure computations, augmented by core, relativistic, quantum electrodynamics, and diagonal Born-Oppenheimer corrections. We also report ab initio calculations of several quantities characterizing the CVRQD PESs, including equilibrium and vibrationally averaged (0 K) structures, harmonic and anharmonic force fields, harmonic vibrational frequencies, vibrational fundamentals, and zero-point energies. They can be considered as the best ab initio estimates of these quantities available today. Results of first-principles computations on the rovibrational energy levels of several isotopologues of the water molecule are also presented, based on the CVRQD PESs and the use of variational nuclear motion calculations employing an exact kinetic energy operator given in orthogonal internal coordinates. The variational nuclear motion calculations also include a simplified treatment of nonadiabatic effects. This sophisticated procedure to compute rovibrational energy levels reproduces all the known rovibrational levels of the water isotopologues considered, H2 O16, H2 O17, H2 O18, and D2 O16, to better than 1 cm-1 on average. Finally, prospects for further improvement of the ground-state adiabatic ab initio PESs of water are discussed.

AB - The high accuracy ab initio adiabatic potential energy surfaces (PESs) of the ground electronic state of the water molecule, determined originally by Polyansky [Science 299, 539 (2003)] and called CVRQD, are extended and carefully characterized and analyzed. The CVRQD potential energy surfaces are obtained from extrapolation to the complete basis set of nearly full configuration interaction valence-only electronic structure computations, augmented by core, relativistic, quantum electrodynamics, and diagonal Born-Oppenheimer corrections. We also report ab initio calculations of several quantities characterizing the CVRQD PESs, including equilibrium and vibrationally averaged (0 K) structures, harmonic and anharmonic force fields, harmonic vibrational frequencies, vibrational fundamentals, and zero-point energies. They can be considered as the best ab initio estimates of these quantities available today. Results of first-principles computations on the rovibrational energy levels of several isotopologues of the water molecule are also presented, based on the CVRQD PESs and the use of variational nuclear motion calculations employing an exact kinetic energy operator given in orthogonal internal coordinates. The variational nuclear motion calculations also include a simplified treatment of nonadiabatic effects. This sophisticated procedure to compute rovibrational energy levels reproduces all the known rovibrational levels of the water isotopologues considered, H2 O16, H2 O17, H2 O18, and D2 O16, to better than 1 cm-1 on average. Finally, prospects for further improvement of the ground-state adiabatic ab initio PESs of water are discussed.

UR - http://www.scopus.com/inward/record.url?scp=33751567029&partnerID=8YFLogxK

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U2 - 10.1063/1.2378766

DO - 10.1063/1.2378766

M3 - Article

VL - 125

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 20

M1 - 204307

ER -