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An Accurate Potential Energy Surface for H2OWe have carried out extensive high quality ab initio electronic structure calculations of the ground state potential energy surface (PES) and dipole moment function (DMF) for H2O. A small adjustment is made to the PES to improve the agreement of line positions from theory and experiment. The theoretical line positions are obtained from variational ro-vibrational calculations using the exact kinetic energy operator. For the lines being fitted, the root-mean-square error was reduced from 6.9 to 0.08 /cm. We were then able to match 30,092 of the 30,117 lines from the HITRAN 96 data base to theoretical lines, and 80% of the line positions differed less than 0.1 /cm. About 3% of the line positions in the experimental data base appear to be incorrect. Theory predicts the existence of many additional weak lines with intensities above the cutoff used in the data base. To obtain results of similar accuracy for HDO, a mass dependent correction to the PH is introduced and is parameterized by simultaneously fitting line positions for HDO and D2O. The mass dependent PH has good predictive value for T2O and HTO. Nonadiabatic effects are not explicitly included. Line strengths for vibrational bands summed over rotational levels usually agree well between theory and experiment, but individual line strengths can differ greatly. A high temperature line list containing about 380 million lines has been generated using the present PES and DMF
Document ID
20020051079
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Schwenke, David W.
(NASA Ames Research Center Moffett Field, CA United States)
Partridge, Harry
(NASA Ames Research Center Moffett Field, CA United States)
Langhoff, Stephen R.
Date Acquired
August 20, 2013
Publication Date
January 1, 1997
Subject Category
Nuclear Physics
Meeting Information
Meeting: Ohio State University 52nd International Symposium on Molecular Spectroscopy
Location: OH
Country: United States
Start Date: June 16, 1997
End Date: June 20, 1997
Funding Number(s)
PROJECT: RTOP 242-80-01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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