An ab initio study of the ground and valence excited states of GaCl

Abstract

All-electron relativistic calculations on the ground and valence excited states of the GaClmolecule have been performed using extended internally contracted multireferenceelectron correlation techniques. The potential energy curves (PECs) of all the 12Λ–S statesand the 23 Ω states generated from them are plotted, and the spectroscopic constants (SCs) of boundstates are fitted. This seems to be the first time that a study has been made ofthe spin–orbit coupling effects of valence states and the transition properties ofA 3Π0+,B 3Π1 andC 1Π1 states of the GaCl molecule in a theoretical way. On comparison of thecalculated results obtained from different multireference electron correlationmethods, we find that the size-extensivity corrections improve the theoreticalTe,re andωe results significantly, and the multireference average quadratic coupled cluster method wellreproduces the experimental values in most cases. The PEC shape and the SCs of theC 1Π1 state are affected by both the avoided crossing rule amongΩ states of the same symmetry and the size-extensivity correction. TheC 1Π1 state has a very shallow potential well . The lifetime of the C 1Π1 state is of the order of a nanosecond, while that of theA 3Π0+ andB 3Π1 states is of the order of a microsecond.