MR-AQCC study on the ground and low-lying excited states of GaI

All-electron relativistic calculations on the ground and low-lying excited states of the GaI molecule have been performed by using internally contracted multireference average quadratic coupled cluster method. The potential energy curves, the spectroscopic constants and the transition properties of these states are obtained. The C 1Π1 state has a rather shallow potential well (ν′max=4) after considering the spin–orbit coupling effect. The observed continuous absorption with maximum at 32 600 cm−1 can be attributed to the transitions from the ground state to the C 1Π1 and nearby states. The radiative lifetime of the C 1Π1 state is of the order of a microsecond, while that of the A 3Π0+ and B 3Π1 states are the order of millisecond.