RELATIONSHIPS BETWEEN BOND-DISSOCIATION ENERGIES, ELECTRON-DENSITY MINIMA AND ELECTROSTATIC POTENTIAL MINIMA

The experimental dissociation energies of a group of homonuclear diato mic molecules are found to correlate with computed electron densities rho(r) and electrostatic potentials V(r) at the bond midpoints, suppor ting an earlier prediction based on density functional arguments (N. H . March, P. M. Kozlowski and F. Perrot 1990, J. molec. Struct. Theoche m, 209, 433). The relationships are generalized to 45 molecules of var ious types, focusing upon the minima of rho(r) and V(r) along internuc lear axes. Dissociation energies are shown to be related distinctly mo re closely to the minimum values of V(r) than to those of rho(r). This complements previous findings for negative monatomic inns as well as the recent observation that the V(r) minima provide the more realistic boundary points between bonded atoms (relative to literature values o f covalent radii), and thus further establishes the significance of el ectrostatic potential axial minima with respect to covalent bonding. I n the present work, all calculations were carried out by a density fun ctional procedure (Becke exchange, Lee, Yang and Parr correlation, 6-3 1G* basis sets).