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Improving upon the ZORA Hamiltonian
Author(s) -
Sadlej Andrzej J.
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.21046
Subject(s) - hamiltonian (control theory) , perturbation (astronomy) , mathematical physics , quantum mechanics , adiabatic quantum computation , quantum , physics , mathematics , quantum computer , mathematical optimization
The metric perturbation method is used to derive what is called the normalized zeroth‐order regular approximation (ZORA) Hamiltonian. This Hamiltonian, although derived in a different way, turns out to be equivalent to the infinite‐order regular approximation (IORA) operator of Dyall and van Lenthe. The normalized ZORA Hamiltonian is analyzed in terms of its expansion with respect to the leading order of the fine structure constant. Through the leading second‐order in the fine structure constant, the normalized ZORA Hamiltonian recovers all terms of what is known as the first‐order regular approximation (FORA). The relation of the regular approximation to methods based on the Douglas–Kroll transformation is discussed. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006