Calculation and Application of Partial Charges

摘要: AbstractCalculation of partial charge is important in chemistry. However, because there are many methods developed, it considerable interest to know how calculate and apply properly address various chemical problems. For basis set, usually double zeta quality acceptable, polarization function would be enough for most cases. To describe electronic state more accurately, Many electron configurations necessary highly strained or anionic species. The NPA population introduced new concept about amide bonds, i.e., the planar geometry nitrogen atom may not come from resonance, but lowering p-orbital energy by electronegative carbonyl carbon atom. issues hypervalent atomic charges was also addressed derivation scheme. When schemes were applied organolithium compounds, ionic nature boding revealed. This comes fact that previous Mulliken overemphasized covalent character, without much justification. other such as NPA(natural analysis), IPP (Integrated Projected Population) showed picture. ESP potential derived generally believed suitable intermolecular interactions, therefore they used molecular dynamics simulations CoMFA (comparative field analysis). using multipole mainly reproduce experimental infrared spectroscopy. In some reports these intermecular electrostatic interactions. Charges density gradient have shown bonds straight, actually bent. proper choice charge-calculation method along with level theory set briefly discussed. Key words : Partial Charge, Molecular Orbital, Population Analysis, Electrostatic Potential, Orbital