ASYMMETRIC SCF COUPLING-COEFFICIENTS FOR HIGHLY SYMMETRICAL OPEN-SHELL MOLECULES

Vector coupling coefficients (VCC), a(mn) and b(mn), appearing in the restricted open-shell Hartree-Fock (ROHF) method, are known to be symm etric: a(mn) = a(nm) and b(nm) = b(nm). We present the results of non- empirical SCF calculations on the states of the methane dication CH4(2 +) (T(d), t2(4)), showing the validity of the use of non-symmetric VCC as well. A similar conclusion has been made in calculations on transi tion metal atoms. Although the SCF results based on the non-symmetric VCC are correct in both the molecular and atomic cases, this conclusio n in itself is in contradiction with existing ROHF theory. A brief dis cussion of this contradiction is presented.