Multi‐determinant trial functions in the determination of the dissociation energy of the beryllium dimer: Quantum Monte Carlo study | Zendy

Harkless J. A. W. | Zendy; Irikura K. K. | Zendy

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Multi‐determinant trial functions in the determination of the dissociation energy of the beryllium dimer: Quantum Monte Carlo study

Author(s) -

Harkless J. A. W.,

Irikura K. K.

Publication year - 2006

Publication title -

international journal of quantum chemistry

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.484

H-Index - 105

eISSN - 1097-461X

pISSN - 0020-7608

DOI - 10.1002/qua.21014

Subject(s) - quantum monte carlo , diffusion monte carlo , monte carlo method , atomic orbital , wave function , basis set , chemistry , dynamic monte carlo method , physics , statistical physics , computational chemistry , atomic physics , hybrid monte carlo , quantum mechanics , electron , mathematics , density functional theory , statistics , markov chain monte carlo

Both variational Monte Carlo (VMC) and fixed‐node diffusion Monte Carlo (DMC) are used to estimate the dissociation energy of Be 2 . The effect of using single‐ and multi‐reference trial functions on the quality of the Monte Carlo estimates is investigated, with independent‐particle wave functions ranging from a restricted Hartree–Fock (RHF) calculation up to a complete active space self‐consistent field (CASSCF) with four valence electrons in 12 active orbitals. It was determined that the best trial function for DMC had a high cutoff for inclusion and included all 2 s and 2 p orbitals in a CASSCF(4,8) calculation. The best DMC estimate, D e = 829(64) cm −1 , compares well with the experimental value of 839(10) cm −1 but is lower than values from the best basis‐set calculations. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006

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