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Kramers' unrestricted Hartree–Fock and second‐order Møller–Plesset perturbation methods using relativistic effective core potentials with spin–orbit operators: Test calculations for HI and CH 3 I
Author(s) -
Kim Yong Suk,
Lee Sang Yeon,
Oh Won Seok,
Park Bo Hyun,
Han Young Kyu,
Park Su Jin,
Lee Yoon Sup
Publication year - 1998
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/(sici)1097-461x(1998)66:1<91::aid-qua7>3.0.co;2-v
Subject(s) - møller–plesset perturbation theory , bond dissociation energy , spinor , relativistic quantum chemistry , chemistry , atomic physics , perturbation theory (quantum mechanics) , hartree–fock method , dissociation (chemistry) , open shell , physics , molecule , quantum mechanics
The Kramers' restricted Hartree–Fock (KRHF) and second‐order Møller–Plesset perturbation (KRMP2) methods using relativistic effective core potentials (RECP) with spin–orbit operators and two‐component spinors are extended to the unrestricted forms, KUHF and KUMP2. As in the conventional unrestricted methods, the KUHF and KUMP2 methods are capable of qualitatively describing the bond breaking for a single bond. As a result, it is possible to estimate spin–orbit effects along the dissociation curve at the HF and MP2 levels of theory as is demonstrated by the test calculations on the ground states of HI and CH 3 I. Since the energy lowering due to spin–orbit interactions is larger for the I atom than for the closed‐shell molecules, dissociation energies are reduced and bond lengths are slightly elongated by the inclusion of the spin–orbit interactions. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 66 : 91–98, 1998