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Ab initio calculations of relativistic and electron correlation effects in polyatomics using the universal Gaussian basis set: XeF 2
Author(s) -
Malli Gulzari L.,
Styszynski Jacek,
Da Silva Alberico B. F.
Publication year - 1995
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.560550302
Subject(s) - ab initio , electronic correlation , basis set , relativistic quantum chemistry , atomic physics , ab initio quantum chemistry methods , physics , gaussian , chemistry , hartree–fock method , electron , wave function , configuration interaction , fock space , quantum mechanics , molecule , excited state
Ab initio accurate all ‐ electron relativistic molecular orbital Dirac–Fock self‐consistent field calculations are reported for the linear symmetric XeF 2 molecule at various internuclear distances with our recently developed relativistic universal Gaussian basis set. The nonrelativistic limit Hartree–Fock calculations were also performed for XeF 2 at various internuclear distances. The relativistic correction to the electronic energy of XeF 2 was calculated as ∼ −215 hartrees (−5850 eV) by using the Dirac–Fock method. The dominant magnetic part of the Breit interaction correction to the nonrelativistic interelectron Coulomb repulsion was included in our calculations by both the Dirac–Fock–Breit self‐consistent field and perturbation methods. The calculated Breit correction is ∼6.5 hartrees (177 eV) for XeF 2 . The relativistic Dirac–Fock as well as the nonrelativistic HF wave functions predict XeF 2 to be unbound , due to neglect of electron correlation effects. These effects were incorporated for XeF 2 by using various ab initio post Hartree–Fock methods. The calculated dissociation energy obtained using the MP 2(full) method with our extensive basis set of 313 primitive Gaussians that included d and f polarization functions on Xe and F is 2.77 eV, whereas the experimental dissociation energy is 2.78 eV. The calculated correlation energy is ∼ −2 hartrees (−54 eV) at the predicted internuclear distance of 1.986 Å, which is in excellent agreement with the experimental Xe—F distance of 1.979 Å in XeF 2 . In summary, electron correlation effects must be included in accurate ab initio calculations since it has been shown here that their inclusion is crucial for obtaining theoretical dissociation energy ( D e ) close to experimental value for XeF 2 . Furthermore, relativistic effects have been shown to make an extremely significant contribution to the total energy and orbital binding energies of XeF 2 . © 1995 John Wiley & Sons, Inc.