Accurate nonrelativistic ground-state energies of 3d transition metal atoms

We present accurate nonrelativistic ground-state energies of the transition metal atoms of the 3d series calculated with Fixed-Node Diffusion Monte Carlo (FN-DMC). Selected multi-determinantal expansions obtained with the CIPSI (Configuration Interaction using a Perturbative Selection made Iterative...

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Bibliographic Details
Published in:The Journal of chemical physics 2014-12, Vol.141 (24), p.244110-244110
Main Authors: Scemama, A, Applencourt, T, Giner, E, Caffarel, M
Format: Article
Language:English
Subjects:
ATOMS
Chemical Sciences
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
CONFIGURATION INTERACTION
Determinants
DIFFUSION
ELECTRON CORRELATION
GROUND STATES
HARTREE-FOCK METHOD
ITERATIVE METHODS
Lower bounds
MONTE CARLO METHOD
Nodes
TRANSITION ELEMENTS
Transition metals
VARIATIONAL METHODS
Wave functions
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Summary:We present accurate nonrelativistic ground-state energies of the transition metal atoms of the 3d series calculated with Fixed-Node Diffusion Monte Carlo (FN-DMC). Selected multi-determinantal expansions obtained with the CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) method and including the most prominent determinants of the full configuration interaction expansion are used as trial wavefunctions. Using a maximum of a few tens of thousands determinants, fixed-node errors on total DMC energies are found to be greatly reduced for some atoms with respect to those obtained with Hartree-Fock nodes. To the best of our knowledge, the FN-DMC/(CIPSI nodes) ground-state energies presented here are the lowest variational total energies reported so far. They differ from the recently recommended non-variational values of McCarthy and Thakkar [J. Chem. Phys. 136, 054107 (2012)] only by a few percents of the correlation energy. Thanks to the variational property of FN-DMC total energies, our results provide exact lower bounds for the absolute value of all-electron correlation energies, |Ec|.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4903985