Molecular reorganization upon ionization and excitation: NH2, NH2+, and NH2minus;systems

摘要

The results ofabinitioselfhyphen;consistent field calculations on NH2+(3B1and1A1), NH2(2B1and2A1), and1A1NH2minus;reveal that the electron distribution in 2a1and 1b2bonding orbitals and in the inhyphen;plane 3a1valence orbital is most affected by ionization or excitation. The formation of the cationic states is accompanied by a shift to the nitrogen atom of 0.35 electron for the1A1and 0.25 electron for the3B1state. In NH2minus;formation, electron density shifts to the hydrogens. These changes occur mainly in the bonding orbitals. Excitation of groundhyphen;state NH2causes a shift of about 0.10 electron onto the nitrogen, whereas excitation of3B1NH2+shifts charge density onto the hydrogens. These changes occur in the valence orbitals. The ionization potential calculated for2B1NH2(11.6 eV) agrees well with experiment, but the photodetachment energy obtained for NH2minus;(0.30 eV) is less than half the experimental value. Polarization functions in the basis set made negligible contributions to the molecular orbitals with the exception of the 2a1bonding orbital. Optimization of the nitrogen polarization functions for the2B1NH2and the NH2minus;systems resulted in only a small improvement in the energy and a more marked change in the charge distribution in NH2minus;.