Franck–Condon simulation of the photoelectron spectrum of AsCl 2 and the photodetachment spectrum of AsCl 2 − employing UCCSD(T)‐F12a potential energy functions: IE and EA of AsCl 2

The currently most reliable theoretical estimates of the adiabatic ionization energies (AIE 0 ) from the X̃ 2 B 1 state of AsCl 2 to the X̃ 1 A 1 and ã 3 B 1 states of AsCl   2 + , and the electron affinity (EA 0 ) of AsCl 2 , including ΔZPE corrections, are calculated as 8.687(11), 11.320(23), and 1.845(12) eV, respectively (estimated uncertainties based on basis‐set effects at the RCCSD(T) level). State‐of‐the‐art ab initio calculations, which include RCCSD(T), CASSCF/MRCI, and explicitly correlated RHF/UCCSD(T)‐F12x (x = a or b) calculations with basis sets of up to quintuple‐zeta quality, have been carried out on the X̃ 2 B 1 state of AsCl 2 , the X̃ 1 A 1 , ã 3 B 1 , and à 1 B 1 states of AsCl   2 + , and the X̃ 1 A 1 state of AsCl   2 − . Relativistic, core correlation and complete basis‐set (CBS) effects have been considered. In addition, computed UCCSD(T)‐F12a potential energy functions of relevant electronic states of AsCl 2 , AsCl   2 + , and AsCl   2 −were used to calculate Franck–Condon factors, which were then used to simulate the valence photoelectron spectrum of AsCl 2 and the photodetachment spectrum of AsCl   2 − , both yet to be recorded. Lastly, we have also computed the AIE and EA values for NCl 2 , PCl 2 , and AsCl 2 at the G4 level and for SbCl 2 at the RCCSD(T)/CBS level. The trends in the AIE and EA values of the group V pnictogen dichlorides, PnCl 2 , where Pn = N, P, As, and Sb, were examined. The AIE and EA of PCl 2 were found to be smaller than those of AsCl 2 , contrary to the order expected from the IE values of P and As. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011