NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Ab Initio Calculations of Water Line StrengthsWe report on the determination of a high quality ab initiu potential energy surface (PES) and dipole moment function for water. This PES is empirically adjusted to improve the agreement between the computed line positions and those from the HITRAN 92 data base with J less than 6 for H2O. The changes in the PES are small, nonetheless including an estimate of core (oxygen 1s) electron correlation greatly improves the agreement with experiment. Using this adjusted PES, we can match 30,092 of the 30,117 transitions in the HITRAN 96 data base for H2O with theoretical lines. The 10,25,50,75, and 90 percentiles of the difference between the calculated and tabulated line positions are -0.11, -0.04, -0.01, 0.02, and 0.07 l/cm. Non-adiabatic effects are not explicitly included. About 3% of the tabulated line positions appear to be incorrect. Similar agreement using this adjusted PES is obtained for the oxygen 17 and oxygen 18 isotopes. For HDO, the agreement is not as good, with root-mean-square error of 0.25 l/cm for lines with J less than 6. This error is reduced to 0.02 l/cm by including a small asymmetric correction to the PES, which is parameterized by simultaneously fitting to HDO md D2O data. Scaling this correction by mass factors yields good results for T2O and HTO. The intensities summed over vibrational bands are usually in good agreement between the calculations and the tabulated results, but individual lines strengths can differ greatly. A high temperature list consisting of 307,721,352 lines is generated for H2O using our PES and dipole moment function.
Document ID
20040053329
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Schwenke, David W.
(NASA Ames Research Center Moffett Field, CA, United States)
Partridge, Harry
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 1998
Subject Category
Atomic And Molecular Physics
Meeting Information
Meeting: Water in the Gas Phase
Location: Paris
Country: France
Start Date: June 21, 1998
End Date: June 24, 1998
Funding Number(s)
PROJECT: RTOP 242-80-01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

There are no available downloads for this record.
No Preview Available