HEAT: High accuracy extrapolated ab initio thermochemistry. III. Additional improvements and overview.
Effects of increased basis-set size as well as a correlated treatment of the diagonal Born-Oppenheimer approximation are studied within the context of the high-accuracy extrapolated ab initio thermochemistry (HEAT) theoretical model chemistry. It is found that the addition of these ostensible improvements does little to increase the overall accuracy of HEAT for the determination of molecular atomization energies. Fortuitous cancellation of high-level effects is shown to give the overall HEAT strategy an accuracy that is, in fact, higher than most of its individual components. In addition, the issue of core-valence electron correlation separation is explored; it is found that approximate additive treatments of the two effects have limitations that are significant in the realm of <1 kJ mol{sup -1} theoretical thermochemistry.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF); Robert A. Welch Foundation; German Research Foundation (DFG); Fonds der Chemichen Industrie
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 967257
- Report Number(s):
- ANL/CSE/JA-60361; JCPSA6; TRN: US200923%%196
- Journal Information:
- J. Chem. Phys., Vol. 128, Issue 2008; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- ENGLISH
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