Wavepacket dynamics study of Cr(CO)(5) after formation by photodissociation: relaxation through an (E circle plus A) circle times e Jahn-Teller conical intersection

In the ultrafast photodissociation of Cr(CO)(6), Cr(CO)(5) is formed within 50 fs. Initially in an excited state, a Jahn-Teller (E circle times e) conical intersection is believed to then act as an efficient decay funnel to the ground state. Here, we present a Hamiltonian representing the first three electronic states of Cr(CO)(5), obtained by fitting the linear vibronic coupling model to calculations using a complete active space self-consistent field (CASSCF) wave-function. The intersection is in fact found to involve ((E circle plus A)circle times e) pseudo-Jahn-Teller coupling, with the singly degenerate state playing an important role. The results of wave-packet dynamics using the multi-configuration time-dependent Hartree (MCTDH) method show that this model is consistent with the experimental data.