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Geometrical derivatives of dipole moments and polarizabilities
Author(s) -
Simons Jack,
Jørgensen Poul
Publication year - 1984
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.560250616
Subject(s) - polarizability , dipole , wave function , hamiltonian (control theory) , moment (physics) , chemistry , computational chemistry , quadratic equation , bond dipole moment , transition dipole moment , physics , quantum electrodynamics , quantum mechanics , mathematics , geometry , molecule , mathematical optimization
Molecular dipole moments and polarizabilities, as well as their geometrical derivatives, are given analytical expressions for multiconfiguration self‐consistent‐field and configuration interaction wavefunctions. By considering the response of the electronic wavefunction induced by electric field and geometrical displacement terms in the Hamiltonian, the response of the total electronic energy to these terms is analyzed. The dipole moment and polarizability are then identified through the factors in the energy which are linear and quadratic in the electric field, respectively. Derivatives with respect to molecular deformation are obtained by identifying factors in these moments which are linear, quadratic, etc., in the distortion parameter. The analytical derivative expressions obtained here are compared to those which arise through finite‐difference calculations, and it is shown how previous configuration‐interaction‐based finite difference dipole moment and polarizability derivatives are wrong. The proper means of treating such derivatives are detailed.