Ab initio calculations and spectral simulation of the Ã2A′→X̃2A″ emission of the HPCl radical

Geometry optimization and harmonic vibrational frequency calculations were carried out at the B3LYP, MP2 and QCISD levels on some low-lying electronic states of HPCl. Relative energies were calculated up to RCCSD(T)/cc-pV5Z(no h)//RCCSD(T)/cc-pVQZ(no g) level. Franck–Condon factors (FCFs) were computed to simulate the recently, first observed Ã2A′→X̃2A″ emission of the HPCl radical [Whitehead et al., Chem. Phys. Lett. 331 (2000) 483]. Ab initio results and spectral simulations from the present study confirm the assignment of the observed spectrum to the Ã2A′→X̃2A″ emission of the HPCl radical, but some of the previous assignments of the observed vibrational structure have been revised.