Electronic Structure of Diatomic Molecules. VII.A. Hartree—Fock Wavefunctions and Energy Quantities for the Ground States of the Second-Row Hydrides, AH

Hartree—Fock wavefunctions are presented for the NaH(X1Σ+), MgH(X2Σ+), AlH(X1Σ+), SiH(X2Πr), PH(X3Σ−), SH(X2Πi), and HCl(X1Σ+) molecules. These are the analytic self-consistent-field wavefunctions obtained from the solutions of the Hartree—Fock—Roothaan equations. Large basis sets of Slater-type functions centered on both nuclei were used and extensive optimization of the orbital exponents has been carried out. The total energies obtained for Re(exptl) are −162.3928, −200.1566, −242.4634, −289.4361, −341.2932, −398.1015, and −460.1103 hartrees, respectively, for the hydrides listed. The first ionization potentials, which are obtained from the Hartree—Fock energy differences between the AH and AH+ systems, are 6.14, 6.76, 7.36, 7.36, 9.65, 9.31, and 11.84 eV, respectively. In addition, potential curves, spectroscopic constants, and certain other energetic quantities are presented. Crude estimates of the correlation energy of the second-row hydrides are made and such quantities are compared within the series and to their respective united and separated atoms. These results suggest that the change in the correlation energy of AH relative to the correct united atom is independent of which hydride is involved. Among the different experimental data for the dissociation energies (De) of MgH and PH, a value of 2.3 for MgH and 3.34 eV for PH are supported by this calculation.