LOCAL-DENSITY STUDIES OF DIATOMIC AB MOLECULES, A, B = C, N, O, F, SI, P, S, AND CL

The spectroscopic constants and charge distribution for the ground sta tes of 36 diatomic molecules containing C to F and Si to Cl atoms have been studied with the deMon density functional program, using the loc al density approximation and large basis sets. For each species, we co mputed the energy and dipole moment at 13 or more internuclear separat ions R. These energies were fitted to polynomials in R - R(e) by least squares, with the value of R(e) determined by iteration. The extracte d coefficients were used to compute spectroscopic constants. The avera ge absolute deviations from experiment were found to be 0.0084 angstro m for R(e), 29 cm-1 for omega(e), 1.11 cm-1 for omega(e)x(e), 0.59 x 1 0(-3) cm-1 for alpha(e), and 1.4 eV for D0. The net charges from Mulli ken population analysis and the dipole moments for the heteronuclear d iatomic molecules are discussed in relationship to the electronegativi ties of the elements. The average absolute difference between mu(upsil on=0)calc and mu(upsilon=0)obs is 0.15 D. Unusual charge distributions were found in CF, NF, OF, CCl, NCl, and OCl.