Molecular physics and chemistry applications of quantum Monte Carlo |
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| Authors: | P J Reynolds R N Barnett B L Hammond W A Lester Jr |
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| Institution: | (1) Materials and Molecular Research Division, Lawrence Berkeley Laboratory, University of California, 94720 Berkeley, California, USA;(2) Department of Chemistry, University of California, 94720 Berkeley, California |
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| Abstract: | We discuss recent work with the diffusion quantum Monte Carlo (QMC) method in its application to molecular systems. The formal correspondence of the imaginary-time Schrödinger equation to a diffusion equation allows one to calculate quantum mechanical expectation values as Monte Carlo averages over an ensemble of random walks. We report work on atomic and molecular total energies, as well as properties including electron affinities, binding energies, reaction barriers, and moments of the electronic charge distribution. A brief discussion is given on how standard QMC must be modified for calculating properties. Calculated energies and properties are presented for a number of molecular systems, including He, F, F?, H2, N, and N2. Recent progress in extending the basic QMC approach to the calculation of “analytic” (as opposed to finite-difference) derivatives of the energy is presented, together with an H2 potential-energy curve obtained using analytic derivatives. |
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| Keywords: | Diffusion quantum Monte Carlo Schr?dinger equation fixed nodes atomic properties molecular properties total energies analytic energy derivatives excited states quadrupole moments binding energies electron affinities |
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