Breathing Orbital Valence Bond Method in Diffusion Monte Carlo: C−H Bond Dissociation of Acetylene<SUP>†</SUP>

ASAP J. Phys. Chem. A, ASAP Article, 10.1021/jp8020062
Web Release Date: July 23, 2008

Breathing Orbital Valence Bond Method in Diffusion Monte Carlo: C−H Bond Dissociation of Acetylene^†

Dominik Domin,^‡ Benoît Braïda,^§^∥ and William A. Lester Jr.^*^‡^⊥

Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California at Berkeley, Berkeley, California 94720-1460, UPMC Université Paris 06, UMR 7616, Laboratoire de Chimie Théorique, Case courrier 137 4 place Jussieu, 75005, Paris, France, CNRS Centre National de la Recherche Scientifique, UMR 7616, 75252 Paris, France, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720

Received: March 6, 2008

Revised Manuscript Received: May 2, 2008

Abstract:

This study explores the use of breathing orbital valence bond (BOVB) trial wave functions for diffusion Monte Carlo (DMC). The approach is applied to the computation of the carbon−hydrogen (C−H) bond dissociation energy (BDE) of acetylene. DMC with BOVB trial wave functions yields a C−H BDE of 132.4 0.9 kcal/mol, which is in excellent accord with the recommended experimental value of 132.8 0.7 kcal/mol. These values are to be compared with DMC results obtained with single determinant trial wave functions, using Hartree−Fock orbitals (137.5 0.5 kcal/mol) and local spin density (LDA) Kohn−Sham orbitals (135.6 0.5 kcal/mol).

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