Correlation of zero-point energy with molecular structure and molecular forces. 3. Approximation for H/D isotope shifts and linear frequency sum rule. [Zero point energies for various protio and deuterio species of water, CH/sub 2/O, CH/sub 4/, C/sub 2/H/sub 4/, C/sub 2/H/sub 6/, C/sub 6/H/sub 6/ were calculated, and the isotopic differences measured]
The approximation methods for the zero-point energy (ZPE) previously developed using the Lanczo's tau method have been applied to the shifts in ZPE due to hydrogen isotope substitutions. Six types of approximation methods have been compared and analyzed on the basis of a weighing function ..cap omega..(lambda) varies as lambda/sup k/ and the actual eigenvalue shift spectra. The method generated by the most general optimzation treatment yields a predictable and generally satisfactory precision of the order of 1% or better. A linear frequency sum rule has been derived, which approximately holds for the sets of isotopic molecules which satisfy the second-order frequency sum rule. 19 references, 3 figures, 3 tables.
- Research Organization:
- State Univ. of New York, Stony Brook
- DOE Contract Number:
- AC02-80ER10612
- OSTI ID:
- 6684409
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 88:10
- Country of Publication:
- United States
- Language:
- English
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