Electron-electron counterbalance density for molecules: Exchange and correlation effects

Numerical results for the electron-electron counterbalance density in a ser ies of molecules are reported. A compact density-dependent expression for t he electron-electron counterbalance density in symmetric systems is used in the discussion of the importance of the exchange and correlation effects i n electron-pair distributions. In addition, the behavior of the electron-el ectron counterbalance density in the dissociation process of the H-2 molecu le is analyzed in the light of the occurrence of strong nondynamical correl ation effects. Finally, the advanced density-dependent expressions allow a direct comparison with the charge concentration index and the electron-elec tron coalescence density, thus revealing the decisive role of exchange and correlation effects in describing the chemical bonding in molecules. (C) 20 01 American Institute of Physics.