Comparison of methods for determining the correlation contribution to hydrogen bond energies

Autor: Janet E. Del Bene, Isaiah Shavitt
Rok vydání: 2009
Předmět:
Zdroj: International Journal of Quantum Chemistry. 36:445-452
ISSN: 1097-461X
0020-7608
DOI: 10.1002/qua.560360846
Popis: The correlation energy contributions to the hydrogen bond energies of complexes (A2H2n+1)+, A2H2n, and (A2H2n–1)− for AHn = OH2, FH, ClH have been evaluated using Moller–Plesset perturbation theory at second (MP2), third (MP3), and fourth (MP4) order; configuration interaction including all single and double excitations (CISD); the averaged coupled-pair functional method (ACPF); and the linearized coupled-cluster method (LCCM), all relative to a single-reference Hartree–Fock function. The CISD energies were corrected for size-consistency errors using the Pople formula and several variants of the Davidson correction and by use of the supermolecule approach for evaluating the binding energies. The Pople formula reduces the size-consistency errors to less than 1 kcal/mol, and the supermolecule approach brings the CISD binding energies, even without correction, into reasonable agreement with the size-consistent methods. The ACPF energies are found to be essentially size consistent in all the complexes studied. Both ACPF and LCCM provide binding energies very close to those of MP3.
Databáze: OpenAIRE
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