Asymmetric localization of titanium in C₂₈

Linear combination of Gaussian-type orbital (LCGTO) local density functional (LDF) calculations on the Ti@C₂₈ endohedral fullerene complex suggest that the titanium atom is too small to fill completely the interior volume of the tetrahedral C₂₈ fullerene and the titanium atom is attracted a significant distance, 0.5 Å, toward one of the four corners of the tetrahedron. This may be one reason why Ti@C₂₈ is experimentally less abundant and stable than U@C₂₈, which has a larger endohedral atom.