Theoretical study of photodissociation dynamics on the lowest-lying Rydberg state of ketene.

In the present study, an attempt is made to reveal the main mechanism of photodissociation on the lowest-lying Rydberg state (1)B(1) of ketene, referred to as the second singlet excited state S(2), by means of the complete active space self-consistent field and the second-order multiconfigurational perturbation theory methods. The located S(2)S(1)T(1) three-surface intersection plays an important role in the dissociation process. It is shown that the intersection permits an efficient internal conversion from S(2) to S(1) state, but prohibits the intersystem crossing from S(2) to T(1) state because of the small spin-orbital coupling value of 0.

Si2CN: a stable nitrogen-containing radical with cyclic ground state.

The structures and isomerization of Si(2)CN species are explored at density functional theory and ab initio levels. Fourteen minimum isomers are located connected by 23 interconversion transition states. At the coupled-cluster single double (CCSD)(T)/6-311+G(2df)//QCISD/6-311G(d) +zero-point vibrational energies level, the thermodynamically most stable isomer is a four-membered ring form cSiSiCN 1 with Si-C cross bonding.