Ab initio calculations and spectral simulation of the (A)over-tilde(2)A '-> (X)over-tilde(2)A '' 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(n o h)//RCCSD(T)/cc-pVQZ(no g) level. Franck-Condon factors (FCFs) were compu ted to simulate the recently, first observed (A) over tilde (2)(A) over til de --> (X) over tilde (2)A" emission of the HPCl radical [Whitehead et al., Chem. Phys. Lett. 331 (2000) 483]. Ab initio results and spectral simulati ons from the present study confirm the assignment of the observed spectrum to the (A) over tilde (2)A --> (X) over tildeA" emission of the HPCl radica l, but some of the previous assignments of the observed vibrational structu re have been revised. (C) 2001 Elsevier Science B.V. All rights reserved.