Ab initio vibrational predissociation dynamics of He-I2(B) complex

Three-dimensional quantum mechanical calculations on the vibrational predissociation dynamics of HeI2 B state complex are performed using a potential energy surface accurately fitted to unrestricted open-shell coupled cluster ab initio data, further enabling extrapolation for large I-2 bond lengths. A Lanczos iterative method with an optimized complex absorbing potential is used to determine energies and lifetimes of the vibrationally predissociating He,I-2(B,v(')) complex for v(')<= 26 of I-2 vibrational excitations. The calculated predissociating state energies agree with recent experimental results within 0.5 cm(-1). This excellent agreement is remarkable since no adjustment was made with respect to the experiments. The present ab initio approach, however, shows its limitations in the fact that the computed lifetimes that are highly sensitive to subtle details of the potential energy surfaces such as anisotropy, are a factor of 1.5 larger than the available experimental data. (c) 2007 American Institute of Physics.