A combined ab initio and Franck–Condon simulation study of the photodetachment spectra of the HCBr− anion

Abstract Geometry optimization and harmonic vibrational frequency calculations have been performed on the X ˜ 2 A ″ state of HCBr − , and X ˜ 1 A ′ and a ˜ 3 A ″ states of HCBr. The term energy and electron affinity of HCBr were calculated and extrapolated to the complete basis set limit. The Duschinsky matrix and displacement vector were calculated at the CCSD(T)/aug-cc-pVQZ level. The normal mode mixing effects played a minor role and can be neglected for the HCBr ( X ˜ 1 A ′ ) – HCBr − ( X ˜ 2 A ″ ) photodetachment. Spectral simulations involved the HCBr ( X ˜ 1 A ′ ) – HCBr − ( X ˜ 2 A ″ ) and HCBr ( a ˜ 3 A ″ ) – HCBr − ( X ˜ 2 A ″ ) photodetachments were carried out on HCBr − at CCSD(T)/aug-cc-pVQZ level, respectively.