Ab initio calculations and spectral simulation of the P2H(X˜2A′)−P2H−(X˜1A′) photodetachment process

Geometry optimization and harmonic vibrational frequency calculations were performed on the X˜2A′ state of P2H and X˜1A′ state of P2H− at the MP2, B3LYP, QCISD and CCSD levels. Franck-Condon factors were computed to simulate the recently observed, photoelectron spectrum of the P2H− anions [K. M. Ervin and W. C. Lineberger, J. Chem. Phys. 122 (2005) 194303]. The theoretical spectra obtained by employing density-functional theory (DFT) with 6-311+G(2p,d) values are in excellent agreement with the observed one. In addition, Franck-Condon analyses and spectral simulations confirm the assignment of the observed spectrum to the X˜2A′−X˜1A′ photodetachment process of P2H−. Using iterative Franck-Condon analysis procedure in the spectral simulations, it is concluded that the reliable variation of geometry is 0.0026 nm for bond length R(PP), 0.0068 nm for bond length R(PH), and 8.3° for bond angle ∠(PPH) from X˜2A′ state of P2H to X˜1A′ state of P2H−.