Molecular polarizability of fullerenes and endohedral metallofullerenes

Abstract The interacting induced dipoles polarization model implemented in our program POLAR is used for the calculation of the molecular dipole µ and tensor quadrupole $\overline{\overline{{\mit \Theta}}}$ moments and also the dipole–dipole polarizability $\overline{\overline{\alpha}}$ . The method is tested with Sc n , C n (fullerene and graphite) and endohedral Sc n @C m clusters. The polarizability is an important quantity for the identification of clusters with different numbers of atoms and even for the separation of isomers. The results for the polarizability are of the same order of magnitude as from reference calculations performed with our version of the program PAPID. The bulk limit for the polarizability is estimated from the Clausius–Mossotti relationship. The polarizability trend for these clusters as a function of size is different from what one might have expected. The clusters are more polarizable than what one might have inferred from the bulk polarizability. Previous theoretical work yielded the same trend for Si n , Ge n and Ga n As m small clusters. However, previous experimental work yielded the opposite trend for Si n , Ga n As m and Ge n Te m larger clusters. At present, the origin of this difference is problematic. One might argue that smaller clusters need not behave like those of intermediate size. The high polarizability of small clusters is attributed to dangling bonds at the surface of the cluster. In this respect, semiconductor clusters resemble metallic clusters. Copyright © 2002 John Wiley & Sons, Ltd.