Using quantum chemistry methods B3LYP/6-31G* to optimize endohedral clusters X@Al₁₂P₁₂ (X＝Li^0/＋, Na^0/＋, K^0/＋, Be^0/2＋, Mg^0/2＋, Ca^0/2＋, H and He), the geometries with the lowest energy were achieved. The geometries, natural bond orbital, dipole moment, adiabatic ionization potential, inclusion energies, vibrational frequency, HOMO-LUMO energy gap and spin density were discussed at the same time. The calculations predict that X＝Na^0/＋, K^0/＋, Mg and He are nearly located at the center of the cage, and Be and Ca^0/2＋ lie in less than 0.033 nm departure from the center. Li^0/＋, Be^2＋, Mg^2＋and H dramatically deviate from the center. The conformations with C₃-symmetry are favored in energies. Al₁₂P₁₂ will prefer to enclose Li^0/＋, Be^0/2＋, Mg^2＋, Ca^2＋and H in it to others.

Key words: endohedral complex, dipole moment, inclusion energy, HOMO-LUMO energy gap, spin density