On the FCNS⇆FC(NS) reaction: A matrix isolation and theoretical study
Abstract The FCNS ⇆ FC(NS) photoisomerization process is a simple model system for molecular switches. Here, we examined the switching processes by experimental and theoretical methods. Prior matrix-isolation IR spectroscopic studies were complemented by matrix-isolation UV spectroscopic measurements to assist the interpretation of the mechanism of the ring closure and opening processes and to verify the accuracy of the computations on the vertical excitation energies. Vertical excitation energies were computed by the EOMEE-CCSD, MCSCF, and MR-CISD methods. Conical intersections were also searched for and three conical intersections along the reaction path FCNS → FC(NS) were located, one co…
First-principles calculation of electron spin-rotation tensors.
Using Curl's Hamiltonian (Curl, R. F. Mol. Phys. 1965, 9, 585) first-principles calculations at the Hartree-Fock and various coupled-cluster (CC) levels based on a perturbative scheme are reported. The effects of basis-set dependence and electron correlation have been investigated by performing benchmark calculations for a set of radicals comprising 12 species and 14 electronic states. In comparison to experimental results, the electron spin-rotation tensor is obtained with a 10-15% accuracy when using the CC singles and doubles approximation and a triple-zeta quality basis set. Some improvements are seen when triple excitations are considered via the CC singles, doubles, and triples model.