A new atomic natural orbital type basis set, which includes high angul
ar momentum functions up to l = 6, has been constructed for tellurium.
Using this set in combination with relativistically corrected multi-r
eference configuration interaction and coupled cluster wavefunctions t
he potential curves of the ground and spectroscopically most important
excited states of the neutral and anionic tellurium dimer have been d
etermined. Predictions for spectroscopic constants and energetic detai
ls such as electron affinity, excitation energies and dissociation ene
rgies, for which in some cases only very limited experimental informat
ion exists, are reported.