Abstract: All structures of X@B₁₂P₁₂ (X=Li^0/+, Na^0/+, K^0/+, Be^0/2+, Mg^0/2+, Ca^0/2+, H and He) are optimized at the B3LYP/6-31G-density functional level of theory, and the corresponding frequency calculations at the same level are used to characterize the optimized structures with energy minima without imaginary frequencies. The geometries，natural bond orbitals (NBO). dipole moments, adiabatic ionization potentials, inclusion energies, vibrational frequencies, energy gaps and spin densities are also discussed． The calculations predict that X= Li, Na^0/+, K^0/+, Mg^0/2+, Ca^0/2+ and He are in the vicinity of 0.006 nm of the cage center, and Be²⁺ is displaced by 0.279 nm from the cage center along the threefold axis of B₁₂P₁₂. Be@B₁₂P₁₂ and H@B₁₂P₁₂ have endohedral Be－B and H－B bonds respectively． Except for Li@B₁₂P₁₂, Be²⁺@B₁₂P₁₂, and He@B₁₂P₁₂, all conformations favor Cs symmetry．

Key words: Endohedral complexes, Dipole moment, Inclusion energies, Energy gap, Spin density