PCCP

The optimized geometry of PCCP(X (1)Sigma(g)(+)) was calculated at a number of levels of theory, yielding a best D-infinity h geometry at the QCISD/6- 311G(2d) level with RP-C = 1.56 Angstrom and RC-C = 1.37 Angstrom; harmonic vibrational frequencies were also calculated. The four lowest cationic sta tes were studied, allowing the lowest four ionization energies to be obtain ed. At the G2 level of theory, the first adiabatic ionization energy was ca lculated to be 9.5 eV. The ordering of the four lowest photoelectron bands is found to be different to NCCN. The adiabatic electron affinity of PCCP i s calculated at the G2 level to be 1.1 eV. Finally, the approximate positio ns of the lowest singlet excited electronic states of the neutral are compu ted.