Many-body polarization accuracy

Following this rationale it can be concluded that the ab initio HF level appears to be the most reliable compromise between accuracy and computational effort to study ions in aqueous solution at present. Despite the shortcomings attributed to a single determi-nantal treatment, the accurate treatment of many-body, polarization, and charge transfer effects in the vicinity of the solute species and the capability to study systems containing hundreds of solvent molecules are key features of QM/MM methods aimed at a reliable description of solution phenomena. However, ongoing hard- and software development will enable the application of more accurate QM techniques within the near future. 

While the form of the GVB wavefunction is appropriate for describing chemical reactions, important many-body effects are neglected in this simple orbital wavefunction. To obtain the needed accuracy effective Cl methods have been and are continuing to be developed. The Cl wavefunctions incorporate to varying degrees the many-body effects omitted in the GVB wavefunction. One of these methods, the Polarization Cl (POL-CI) method,has been found to provide a useful description of the energetics of a wide range of chemical reactions. The POL-CI method is closely related to the first-... 

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