Theoretical calculations for the prereaction processes of the D ••• HF and H ••• DF van der Waals molecules

We present the computational results on the photo-induced prereaction processes, D . . . HF + hv --> DH + F and H . . . DF + hv --> HD + F. The calculations were carried out using the three-dimensional time-independent quantum reactive scattering method with hyperspherical coordinates. The accurate ab initio potential energy surface of Stark and Werner has been employed in the theoretical calculations. We have found that prereaction occurs with a relatively large probability for the D . . . HF + hv --> DH + F process but the prereaction probability for H . . . DF + hv --> HD + F was found to be very small. This difference is due to tunneling which plays a crucial role in prereaction. (C) 2001 Elsevier Science B.V. All rights reserved.