A RASSCF study of free base, magnesium and zinc porphyrins: accuracy versus efficiency

作者：Kerridge Andrew^*

来源：Physical Chemistry Chemical Physics, 2013, 15(6): 2197-2209.

DOI：10.1039/c2cp43982d

The restricted-active-space self-consistent-field methodology is successfully applied to the study of free base-and regular metalloporphyrins, the latter containing magnesium and zinc central ions. It is shown that inclusion of all excitations involving the Gouterman frontier orbitals in the RAS2 subspace results in a numerically stable approach, producing highly accurate results at a fraction of the computational cost of the complete-active-space self-consistent-field method, whereas increasing RAS2 beyond this size leads to only modest improvement. Topological and orbital analysis shows that the approach is also able to give a highly accurate description of the electronic wavefunction. Inclusion of the entire p-conjugated subsystem in the active space results in more accurate excitation energies and a reduction in the dependence on the exact form of the perturbational Hamiltonian used to include dynamic correlation. The larger active space also resolves a quantitative disagreement in results obtained with and without the inclusion of dynamic correlation.

• 出版日期2013