Electronic Structure of Ammonia

A self-consistent field calculation of the normal state of the ammonia molecule is made in the molecular orbital approximation. The molecular orbitals are expressed as linear combinations of all valence and inner shell orbitals of the atoms, and all interactions of the ten electrons are included. The total molecular energy, —56.096 au, is 99.2% of the experimental value. The dissociation energy, 0.3308 au, is about 72% of the experimental value. The calculated dipole moment (1.486 Debye) is almost equal to the experimental value (1.46D). The two lowest ionization potentials are calculated as 9.94 and 16.20 ev, and are probably within one ev of the experimental values. An equivalent orbital representation is obtained from the molecular orbitals and directional features of distribution of electron density are discussed. The integrals over atomic orbitals were all evaluated by standard mathematical methods, which is discussed in an appendix.