POTENTIAL CURVES AND SPECTRA OF CIO- AND HOCI SPECIES STUDIED BY AB INITIO METHODS

Abstract

Potential energy curves of the ground and few excited states of the ClO- and HOCl species along the photodissociation reaction channels, which correlate with the low lying dissociation limits are obtained on the ground of multireference configuration interaction. The singlet - triplet nonadiabatic transition during predissociation of the ground Х1 state to the lowest limit О(3Р) + Cl-(1S) is predicted on the base calculations results. In order to predict the possible importance of the singlet-triplet absorption in the HOCl molecule spectrum we have presented potential energy curves for the ground singlet X1Aand the first excited triplet 13A states. The results show that atmospheric photochemistry of heavy halogen-containing compounds depends essentially on the singlet-triplet transitions and inclusion of relativistic effects. Thermochemical ab initio calculations for ClO– as possible dissociation products of HOCl molecule show that these compounds in the singlet ground state are stable enough. Our multireference configuration interaction calculations including spin – orbit coupling indicate that the compounds are metastable.