First-principles prediction and partial characterization of the vibrational states of water up to dissociation

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• 作者：Attila G. Csá ; szá ; r ; Edit Má ; tyus ; Tamá ; s Szidarovszky ; Lorenzo Lodi ; Nikolai F. Zobov ; Sergei V. Shirin ; Oleg L. Polyansky ; Jonathan Tennyson
• 关键词：Water vapor ; Transition wavenumbers ; Atmospheric physics ; Energy levels ; Assignation
• 刊名：Journal of Quantitative Spectroscopy and Radiative Transfer
• 出版年：2010
• 出版时间：June 2010
• 年：2010
• 卷：111
• 期：9
• 页码：1043-1064
• 全文大小：1147 K

文摘

A new, accurate, global, mass-independent, first-principles potential energy surface (PES) is presented for the ground electronic state of the water molecule. The PES is based on 2200 energy points computed at the all-electron aug-cc-pCV6Z IC-MRCI(8,2) level of electronic structure theory and includes the relativistic one-electron mass-velocity and Darwin corrections. For H₂ ¹⁶O, the PES has a dissociation energy of D₀ = 41 109 cm⁻¹ and supports 1150 vibrational energy levels up to 41 083 cm⁻¹. The deviation between the computed and the experimentally measured energy levels is below 15 cm⁻¹ for all the states with energies less than 39 000 cm⁻¹. Characterization of approximate vibrational quantum numbers is performed using several techniques: energy decomposition, wave function plots, normal mode distribution, expectation values of the squares of internal coordinates, and perturbing the bending part of the PES. Vibrational normal mode labels, though often not physically meaningful, have been assigned to all the states below 26 500 cm⁻¹ and to many more above it, including some highly excited stretching states all the way to dissociation. Issues to do with calculating vibrational band intensities for the higher-lying states are discussed.