Radial moments of the electron density: Gas phase results and the effects of solvation

The radial moments of the electron density, < r(n)>, have been calculated f or N-2 and H2O at the quadratic configuration interaction (with singles and doubles) levels of theory by use of a variety of basis sets. An optimal ba sis set was chosen from the first set of calculations and then used with se veral conventional ab initio and density functional methods to compute the moments for a representative set of molecules: N-2, CO, CH4, NH3, H2O, HF, SiH4, PH3, H2S, HCl, CH3OH, and CH3SH. The effects of solvation on the radi al moments were also studied using the Onsager model and an extension of th e Tomasi polarized continuum model. (C) 2000 American Institute of Physics. [S0021-9606(00)31103-5].