Vibrational analysis of fullerenes by valence force-field calculations

Summary form only given. Since the discovery and the synthesis of the new forms of carbons, the fullerenes, numerous experimental and theoretical works have been carried out. Among them Raman Scattering has proved to be a tool of significant importance to characterize and study C/sub 60/, C/sub 70/... and isotope derivates, as well as the alkali doped compounds in their different phases. We present in this paper a vibrational analysis by using a valence force-field model, in which the bond-stretching force constants are determined for both C = C and C-C bonds. Results are compared to previous models found in the literature (1). Also, simplified calculations based on orbital overlaps leads to the determination of electronic levels when position can be expressed by using the overlap parameters /spl beta//sub 1/ et /spl beta//sub 2/. The correlation between the valence force-field and electronic levels will be discussed. The parameters found in our calculations will also be compared to those found in conducting polymers for carbon-carbon bonds.