Validity of a hybrid quantum/classical approach in photodissociation/recombination of I2 in rare gas matrices

In this work, we examine the validity of a hybrid quantum/classical method used to study the photodissociation/recombination dynamics of I2(A) in rare gas matrices. Our simplified model includes a I2 molecule embedded in a linear chain of rare gas atoms (Kr or Xe). The aggregate is partitioned into a quantum system and a classical bath and their dynamics are coupled self-consistently within the Ehrenfest framework. Two partitioning schemes are used. The first scheme treats the I–I coordinate quantum mechanically and the rare gas coordinates classically. The second and more reliable scheme includes in the quantum system both the I–I mode and the symmetric motion of the two nearest rare gas atoms. Both models show substantial energy transfer from the dissociating iodine to the solvent, followed by coherent vibrational motion in the recombined I2. It is found that the one-dimensional quantum/classical scheme is consistent with its higher dimensional counterpart, although the latter shows much faster dephasing.