Calculation of the electronic structure of transition metalhexafluoro-compounds by the MO LCAO method with averaging with respect to configuration
| Autor: | A. E. Nikiforov, A. P. Khaimenov, S. Yu. Shashkin, V. I. Cherepanov |
|---|---|
| Rok vydání: | 1980 |
| Předmět: |
Physics
education.field_of_study Population Electronic structure Kinetic energy Inorganic Chemistry symbols.namesake Operator (computer programming) Core electron Linear combination of atomic orbitals Excited state Quantum mechanics Materials Chemistry symbols Physical and Theoretical Chemistry Atomic physics education Hamiltonian (quantum mechanics) |
| Zdroj: | Journal of Structural Chemistry. 20:606-608 |
| ISSN: | 1573-8779 0022-4766 |
| Popis: | where H is the operator of the kinetic energy and the energy of attraction of the electron to the nuclei shielded by the core electrons, aiu is the population of the i-thatomic orbital at the center u, Jiu and Kiu are the Coulomb and exchange operators, constructed on the i-thAO of the center'u. Self-consistency was achieved for the ground (t~ge~} and excited (t52ge~) configurations. ~ae parameter 10Dq was determined as the difference in the oneelectron orbital energies 5 3 ~0~q = ~ ( e g, ~ g e g) --~ (~, t~ogj.~ (2) It may be noted that Eq. (2) is applicable only in the approximation of "frozen MO," and with allowance for the presence of open shells the effective one-electron operator used in Eq. (2) differs from the operator defining the coefficients in the MO [5]. The authors of [1-4] studied different approaches to the analysis of the populations and the influence of the choice of basis functions, but even the most successful versions of the method give d-level populations which are too high, compared with nonempirical calculations [4, 7], and overestimate the covalency of the t2g- and eg-MO. In [8] a semi-empirical version was proposed for calculating the specific features of the open shells of a complex in the approximation involving averaging of the many-electron energy with respect to the terms of the configuration. For the systematic semi-empirical calculation, assuming a self-consistent solution of different Hartree--Fock equations for open and filled MO of the same symmetry, it is necessary to have reliabIe approximate expressions for the matrix elements (ME) of the operators of their orthogonalizatio n with respect to one another. Allowance for these expressions complicates considerably the usual calculation procedure, so that in the present work it is assumed that the composition of all the MO can be obtained with one effective Hamiltonian, that is that all the MO, as in [1-4], are obtained from the solution of the secular equation with the operator (1). The 10Dq is determined using the many-electron approach with allowance for the presence of open levels, proposed in [8], where the following expression was obtained for the energy of the configuration, averaged with respect to the terms |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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