The potential energy surface of exohedral HeC36 is analyzed in detail and extrapolated to the complete basis set limit using Moller- Plesset perturbation calculations. A limited number of coupled cluster singles and doubles calculations has also been performed. Exohedral complexes above the hexagonal faces toward the major axis are found to be the most stable, but the helium atom can move almost freely from the equator to the poles of C-36 without dissociating the complex due to the disparity of masses. The effective 1D interaction potential has van der Waals attributes in good agreement with those estimated from He-2 and a Girifalco function for the C-36 dimer, supporting three bound states. (c) 2008 Elsevier B. V. All rights reserved.