Quantum chemistry polarization effects

The late Pierre Claverie was one of the most influential French researchers in the field of intermolecular interactions. His work dedicated to the foundation of molecular force fields and their links with quantum chemistry was truly visionary. Since about 1970, Claverie has pointed out the importance of taking polarization effects into account in molecular mechanics, and he proposed the concept of self-encased different levels of computations regarding solvent effects, thereby showing the road to the present development of hybrid quantum mechanics/molecular mechanics (QMVMM) methods. 

An adequate account of the electron correlation effects requires the use of basis sets of considerable sizes which include polarization and diffuse functions. The ab initio CC calculations with such basis sets are expensive. Thus more exact CC calculations of molecular optical parameters can be carried out only for relatively small molecules. In the calculations of polarizabilities and hyperpolarizabilities for larger a -systems more approximate methods need to be used. Such calculations still remain a difficult problem in quantum chemistry. 

Reynolds W (1980) An approach for assessing the relative importance of field and o-inductive contributions to polar substituent effects. J Chem Soc Perkin Trans II 985-992 Jorgensen CK (1963) Optical electronegativities of 3d group central ions. Mol Phys 6 43 7 Jorgensen CK (1975) Photo-electron spectra of non-metaUic sohds and consequences for quantum chemistry. Structure and Bonding 24 1-58... 

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