Modelling the C-13 NMR chemical shifts of C-84 fullerenes

Simulations of C-13 NMR shielding constants for fullerenes, based on the de nsity-functional based tight-binding (DFTB) and individual gauge for local orbitals (IGLO) methods, are presented. This IGLO-DFTB model incorporates a correction scheme for the energies of the virtual states together with one empirical scaling factor. The IGLO-DFTB chemical shifts for a large test s et of fullerenes are well correlated with those from ab initio calculations . Chemical shifts of the 24 isolated-pentagon isomers C-84 are evaluated an d compared with recent experimental work. (C) 2000 Elsevier Science B.V. Al l rights reserved.