Journal of Structural Chemistry

, Volume 39, Issue 4, pp 484–488 | Cite as

Orbital relaxation and molecular properties of silicon compounds

  • A. I. Ermakov
  • A. E. Merkulov


A model that includes orbital relaxation in ab initio quantum chemical calculations of molecular systems is proposed. The role of orbital relaxation in determination of molecular properties is studied in the following series of silicon compounds: SiHnF{4−n} (n = 0−4), H3SiX, and SiX4 (X = H, Cl, CH3, OH, F). It is shown that orbital relaxation always decreases the total energy of a molecule and leads to better agreement between the calculated and experimental equilibrium distances and dissociation energies. The orbital relaxation effect decreases in the following series of chemical bonds: Si-F > Si-C > Si-O > Si-Cl > SiH. Calculation of the ionization energies of molecules in terms of Koopmans’ theorem including orbital relaxation gives better or worse agreement with experiment. Inclusion of orbital relaxation does not improve the description of the dipole moments of polar molecules. Studying the contribution of orbital relaxation allows one to clarify the role of silicon d-orbitals in the electronic structure of silicon compounds. The silicon d-orbitals are shown to be of independent significance in the formation of chemical Si-O and Si-F bonds.


Silicon Compound Valence Orbital Methylsilane Silyl Derivative Orbital Occupancy 


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Copyright information

© Kluwer Academic/Plenum Publishers 1998

Authors and Affiliations

  • A. I. Ermakov
    • 1
  • A. E. Merkulov
    • 1
  1. 1.Novomoskovsk Institute of D. I. Mendeleev Russian Chemical Engineering UniversityUSSR

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