Q.
Excited and ionized states of the porphyrin compounds
A. To calculate the absorption
spectrum of porphyrin compounds, we recommend at
least valence double-zeta plus polarization d-functions on C and N atoms.
However, the effect of polarization function was not so significant in the
low-lying singlet excited states. See our previous study published in J. Phys.
Chem. A 102(10),
1843-1849 (1998). For
calculating the ionized states, we recommend including the
polarization d-functions on C and N atoms.