PCCP

Abstract

The optimized geometry of PCCP(X¹Σ_g⁺) was calculated at a number of levels of theory, yielding a best D_∞h geometry at the QCISD/6-311G(2d) level with R_P-C=1.56Åand R_C-C=1.37Å; harmonic vibrational frequencies were also calculated. The four lowest cationic states were studied, allowing the lowest four ionization energies to be obtained. At the G2 level of theory, the first adiabatic ionization energy was calculated 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 is calculated at the G2 level to be 1.1 eV. Finally, the approximate positions of the lowest singlet excited electronic states of the neutral are computed.