Electronic Electrostatic Potentials of Molecules, Local Hardness, Local Polarizability and Local Ionization Energy

The significance of the total molecular electrostatic potential Vtot(r) is well established. However much less attention has been given to its component due to the electrons alone, Vel(r). In this paper, we examine the features of Vel(r) for a group of six molecules, and contrast them to those of Vtot(r). We also assess a proposed relationship between |Vel(r)| and local hardness &eta(r), an index of chemical reactivity. We conclude that it is not generally valid, and that better measures of η(r) are the local ionization energy IS(r) and the inverse of the local polarizability α(r).