TY - JOUR
T1 - An analytical fit to an accurate ab initio (1A1) potential surface of H2O
AU - Redmon, Michael J.
AU - Schatz, George C.
N1 - Funding Information:
CC. Schatz thanks NSF &ant CHE-7820336 for partia! support. He also thanks M J. Redmon for his generous hospitality during his stay at Batelle Labs. The authors thank RJ. Bartlett, I. Shavitt and G.D. Purvis III for useful discussions. They also thank J-N. Mtarrell for helpful correspondence on the Sorbie-Murreil surface, and R. Schinke and W.A. Lester Jr. for comments on their surface and for providing a preprint of their work prior to publication. This work was supported in , lart by the Air Force Office of Scientific Research, United States Air Force (AFSC), under Contract No, F49620-79X-0050, and 0y the Air Force Rocket Propulsion Laboratory, United States Air Force (ABC), under Contract No. F04611-794024. The United States Government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright notation hereon.
PY - 1981/1/15
Y1 - 1981/1/15
N2 - The accurate ab initio MBPT quartic force field of Bartlett, Shavitt and Purvis has been fit to an analytical function using a method developed by Sorbie and Murrell (SM). An analysis of this surface indicates that it describes most properties of the H2O molecule very accurately, including an exact fit to the MBPT force field, and very close to the correct energy difference between linear and equilibrium H2O. The surface also reproduces the correct diatomic potentials in all dissociative regions, but some aspects of it in the "near asymptotic" O(1D) + H2 region are not quantitatively described. For example, the potential seems to be too attractive at long range for O + H2 encounters, although it does have the correct minimum energy path geometry and correctly exhibits no barrier to O atom insertion. Comparisons of this surface with one previously developed by SM indicates generally good agreement between the two, especially after some of the SM parameters were corrected, using a numerical differentiation algorithm to evaluate them. A surface developed by Schinke and Lester (SL) is more realistic than outs in the O(1D) + H2 regions, but less quantitative in its description of the H2O molecule. Overall, the present fit appears to be both realistic and quantitative for energy displacements up to 3-4; eV from H2O equilibrium, and should therefore be useful for spectroscopic and collision dynamics studies involving H2O.
AB - The accurate ab initio MBPT quartic force field of Bartlett, Shavitt and Purvis has been fit to an analytical function using a method developed by Sorbie and Murrell (SM). An analysis of this surface indicates that it describes most properties of the H2O molecule very accurately, including an exact fit to the MBPT force field, and very close to the correct energy difference between linear and equilibrium H2O. The surface also reproduces the correct diatomic potentials in all dissociative regions, but some aspects of it in the "near asymptotic" O(1D) + H2 region are not quantitatively described. For example, the potential seems to be too attractive at long range for O + H2 encounters, although it does have the correct minimum energy path geometry and correctly exhibits no barrier to O atom insertion. Comparisons of this surface with one previously developed by SM indicates generally good agreement between the two, especially after some of the SM parameters were corrected, using a numerical differentiation algorithm to evaluate them. A surface developed by Schinke and Lester (SL) is more realistic than outs in the O(1D) + H2 regions, but less quantitative in its description of the H2O molecule. Overall, the present fit appears to be both realistic and quantitative for energy displacements up to 3-4; eV from H2O equilibrium, and should therefore be useful for spectroscopic and collision dynamics studies involving H2O.
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U2 - 10.1016/0301-0104(81)85112-9
DO - 10.1016/0301-0104(81)85112-9
M3 - Article
AN - SCOPUS:0012919587
VL - 54
SP - 365
EP - 374
JO - Chemical Physics
JF - Chemical Physics
SN - 0301-0104
IS - 3
ER -