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Theory of intermolecular interactions: The long range terms in the dipole–dipole, monopoles–dipole, and monopoles–bond polarizabilities approximations
Author(s) -
Claverie Pierre,
Rein Robert
Publication year - 1969
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.560030502
Subject(s) - dipole , hamiltonian (control theory) , intermolecular force , charge (physics) , point particle , physics , bond dipole moment , polarizability , atomic physics , range (aeronautics) , chemistry , electrostatics , london dispersion force , molecular physics , quantum mechanics , molecule , transition dipole moment , van der waals force , materials science , mathematics , composite material , mathematical optimization
The problem of evaluating the long range terms (electrostatic, polarization, dispersion) of the interaction energy between molecules at intermediate distances (i.e. distances of the order of magnitude of the molecular dimensions) is considered. Instead of being approximated by its dipole part, the exact interaction Hamiltonian is treated as proposed by Longuet‐Higgins [11], i.e. the matrix elements are interpreted as electrostatic interactions between state and transition charge distributions. These charge distributions are approximated in a systematic way by sets of point charges (localized on the atoms) or sets of dipoles (localized on the bonds). The various contributions to the energy may then be expressed in terms of atomic net charges and bond polarizabilities. More refined approximations of the charge distributions could be used and correspondingly improved formulae could be derived: as an example, a formula for the σ‐π dispersion energy is derived, where the σ charge distributions are approximated by bond transition dipoles (leading to σ bond polarizabilities in the final formula) while the π charge distributions are approximated by atomic charges.