On chemical bonding of Helium with hcp-Beryllium
  Chemical inertness is the key property of helium determining its solubility, distribution and accumulation kinetics in metals. Against all expectations, our ab initio calculations show a substantial chemical bonding between He and Be atoms in the hcp-Be matrix when He occupies a non-symmetric position in a basal plane. 
A. S. Bakai, A. N. Timoshevskii, B. Z. Yanchitsky
cond-mat.mtrl-sci