Laboratoire Francis PERRIN
URA CNRS-CEA 2453
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Computational Chemistry for Experimentalists: Predictions of Thermodynamic Properties Beyond 0 K: Séminaires SPAM LFP
vers calendrier
15/05/2008 à 11h00
LIDYL Bât 522, p 138 CEA-Saclay
Jerzy Leszczynski

The results of comprehensive investigations performed to refine the procedure for calculations of Gibbs free energy with a relative accuracy of less than 1 kcal/mol are reported. Fifteen benchmark intermolecular complexes are examined via several quantum-chemical methods, including the second-order Moller-Plesset perturbation (MP2), coupled cluster (CCSD(T)), and density functional (BLYP, B3LYP) theories augmented by Dunnings correlation-consistent basis sets. The effects of electron correlation, basis set size, and anharmonicity are systematically analyzed, and compared with available experimental data. The results of the calculations suggest that experimental accuracy can be reached only by extrapolation of MP2 and CCSD(T) total energies to the complete basis set. The contribution of anharmonicity to the zero point energy and T Sint values is fairly small. The new, economic way to reach chemical accuracy in the calculations of the thermodynamic parameters of intermolecular interactions is proposed.