Self-Consistent-Field Wavefunctions and Computed Potential-Energy Curves for the NH3 and NH Molecules, in One-Center Approximation

Single-determinant self-consistent field wavefunctions calculated by the one-center expansion method are reported for the NH3 and NH molecules. The molecular orbitals were expanded in terms of symmetry adapted Slater-type orbitals centered at the heavy nucleus. To obtain the potential-energy curve for the NH3 molecule corresponding to the tunneling motion of the N atom through the H3 plane, the calculations were carried out for twelve different geometrical configurations. In the present work only those geometrical configurations of NH3 are considered for which all three N–H distances are the same, and are denoted by RNH(NH3). For each geometrical configuration of NH3, defined by a fixed value of the bond angle (or the apex angle), the optimum values of RNH(NH3) and basis function exponents were determined. For the NH molecule, the calculations were carried out at seven different internuclear distances, RNH. At each RNH, the best basis function exponents were determined. These seven points were used to construct the potential-energy curve of NH. For NH3 in the equilibrium configuration, the calculated values for the bond length, bond angle, total energy, dipole moment, and the first ionization potential, are 1.867 bohr, 109.342°, −56.084186 hartree, 0.5993 a.u. (1.5231 D) and 0.4155 hartree, respectively. For planar NH3, the calculated bond length, total energy, and the first ionization potential are 1.853 bohr, −56.043064 and 0.3836 hartree, respectively. For the NH molecule, the calculated equilibrium bond length, total energy, dipole moment, and the 1π orbital energy are 1.90 bohr, −54.90638 hartree, 0.7515 a.u. (1.9100 D), and 0.5281 hartree, respectively.