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Economical treatments of relativistic effects and electron correlation in WH 6
Author(s) -
Hertwig Roland H.,
Koch Wolfram,
Yates Brian F.
Publication year - 1998
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/(sici)1096-987x(19981115)19:14<1604::aid-jcc6>3.0.co;2-n
Subject(s) - relativistic quantum chemistry , coupled cluster , physics , hamiltonian (control theory) , electronic correlation , pauli exclusion principle , perturbation theory (quantum mechanics) , electron , scalar (mathematics) , quantum mechanics , atomic physics , molecule , mathematics , mathematical optimization , geometry
The equilibrium geometries and relative stabilities of several structural isomers of tungsten hexahydride, WH 6 , have been obtained at different levels of quantum chemical calculations. The performance of various strategies to (i) include electron correlation, viz. density functional theory based approaches, Møller/Plesset perturbation and coupled cluster theory, and to (ii) account for scalar relativistic effects, viz. various relativistic effective core potentials, first order perturbation theory, a quasi‐relativistic treatment employing a Pauli Hamiltonian, and use of the Douglas/Kroll operator, are compared to the best theoretical data available. It is shown that relativistic and electron correlation effects are most important for the high‐symmetry species, that these effects give rise to opposite trends in relative energies, and that overall the relativistic effects dominate. The most efficient way to incorporate relativistic effects appears to be via the use of relativistic effective core potentials, while the correlation energies are best taken account of using a conventional method such as CCSD(T). © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1604–1611, 1998