title: A fixed-node diffusion Monte Carlo study of the 1,2,3-tridehydrobenzene triradical.
abstract: The electronic structure of 1,2,3-tridehydrobenzene was investigated using quantum Monte Carlo methods. The radical contains two low-lying electronic states that are nearly degenerate adiabatically (within 2 kcal/mol separation), according to previous coupled cluster calculations. We performed Diffusion Monte Carlo (DMC) calculations starting from Multi-Reference Configuration Interaction (MRCI) trial wavefunctions, with a complete active space (CAS) containing 9 electrons in 9 orbitals, CAS(9,9). Our converged DMC results are in close agreement with the best coupled-cluster results, and further strengthen the assignment of a (2)A1 ground state.
authors.affiliation: Physical and Life Sciences Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA.
authors.forename: Lucas
authors.initials: L
authors.lastname: Koziol
authors.affiliation: Physical and Life Sciences Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA.
authors.forename: Miguel M
authors.initials: MM
authors.lastname: Morales