The zero-field splitting (zfs) parameter D of benzene and naphthalene in th
eir lowest excited triplet state has been calculated within the framework o
f spin-coupled valence bond theory. The predicted parameters of these molec
ules turn out to be 0.168 cm(-1) and 0.124 cm(-1), respectively, in reasona
bly good agreement with the observed values of 0.159 cm(-1) and 0.101 cm(-1
). (C) 2000 American Institute of Physics. [S0021-9606(00)31203-X].