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First‐order relativistic corrections to MP2 energy from standard gradient codes: Comparison with results from density functional theory
Author(s) -
Franke Robert,
Van Wüllen Christoph
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<1596::aid-jcc5>3.0.co;2-e
Subject(s) - relativistic quantum chemistry , physics , hamiltonian (control theory) , theory of relativity , perturbation theory (quantum mechanics) , electronic correlation , spinor , quantum mechanics , quantum electrodynamics , classical mechanics , mathematical physics , electron , mathematics , mathematical optimization
The evaluation of the first‐order scalar relativistic corrections to MP2 energy based on either direct perturbation theory or the mass–velocity and Darwin terms is discussed. In a basis set of Lévy‐Leblond spinors the one‐ and two‐electron matrix elements of the relativistic Hamiltonian can be decomposed into a nonrelativistic part and a relativistic perturbation. Thus, a program capable of calculating nonrelativistic energy gradients can be used to calculate the cross‐term between relativity and correlation. The method has been applied to selected closed‐shell atoms (He, Be, Ne, and Ar) and molecules (CuH, AgH, and AuH). The calculated equilibrium distances and harmonic frequencies were compared with results from first‐order relativistic density functional calculations. It was found that the cross‐term is not the origin of the nonadditivity of relativistic and correlation effects. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1596–1603, 1998