Finally we examine an unusual linear molecule, which is the result of insertion of Be into HCl, yielding H -Be -Cl. While H -Cl is polarized as H δ+ Cl δ-, Be has lower electronegativity than H, and so there will be substantial charge transfer. Indeed the ionic limit would be H -Be 2+ Cl -. What then, is the actual charge distribution when we consider the covalent character of the molecular orbitals? The calculated populations are shown in Fig. , and it is immediately evident that predicted charges on Be vary widely. The least polar picture comes from ChElPG and MAO, with q(Be)≈+0.5, while the IAO scheme suggests q(Be)≈+1. 35. How should we understand this dramatic difference and suggest which might be more correct?