Abstract
A detailed calculation of the chemical shift tensor in trigonal selenium and tellurium is presented. It is based on a tight-binding model where interactions between suitably defined molecular orbitals are taken into account by second order perturbation theory. The diagonal part of the tensor can completely be interpreted using reasonable values for the parameters. The results are in agreement with optical results which show that there is a substantial amount of bonding character in the upper valence band. With these values for the parameters the model cannot reproduce the sign of the non diagonal term. Possible reasons for this discrepancy are discussed