Graphite and graphitic compounds: vibrational spectra from oligomers to real materials

An empirical valence force-field has been obtained for an ideal two-dimensional crystal of graphite. This force field is the generalization to the infinite case of the force field developed by Ohno (in K. Ohno, J. Chem. Phys. 95 (1991) 5524; K. Ohno, J. Mol. Spectrosc. 72 (1978) 238) for simple Polycyclic Aromatic Hydrocarbons (PAH). Based on classical dynamical calculations we have clarified the origin of the Raman bands observed in PAH and have rationalized their correlation with the Raman features observed in graphitic materials with different degree of purity and crystalline order. (C) 1999 Elsevier Science B.V. All rights reserved.