ZEEMAN-EFFECT IN T-1U SYMMETRY VIBRATIONAL-STATES OF C-60 FULLERENE

Theoretical analysis of the vibrational magnetic moments for the four T-1u fundamental vibrational states of the C-60 fullerene molecule is reported. An attempt to determine these moments is made in terms of a theory which includes both mechanical and vibronic contributions. At t his level the theory leads to magnetic moments which are consistent in sign and relative magnitude with those measured for nu(3)=1183 cm-(1) and nu(4)=1430 cm-(1) vibrations of C-60 using magnetic vibrational c ircular dichroism. Predictions for the lower energy vibrations at nu(1 )=528 cm-(1) and nu(2)=577 cm-(1) are also provided. The moments of th ese latter transitions appear to arise almost totally from the mechani cal (ground state) terms in the theory while those of higher energy mo des have both vibronic and mechanical contributions. For the nu(4) vib ration the absolute magnitude of the combined vibronic and nuclear con tributions was found to be larger than found in MVCD experiment. This may be due to the severe approximations implicit in the SCFPPP-CI meth od used.