Permeation of second row neutral elements through Al₁₂P₁₂ and B₁₂P₁₂ nanocages; a first-principles study

Both exohedral and endohedral complexes of second row elements doped X₁₂Y₁₂ (X = B, Al and Y = P) nano-cages are evaluated for thermodynamic stabilities, electronic properties and kinetic barriers. Interaction energies are calculated to deeply perceive the stability of these complexes. Further, interconversion of exohedral and endohedral complexes is explored through an unprecedented approach, where 2nd row elements translate into nano-cages through boundary crossing. Subsequently, the kinetic barriers for encapsulation and decapsulation are also investigated through PES scanning of all elements by passing through hexagon of nano-cages. Systematic investigations revealed that due to larger diameter, AlP nanocage exhibits low encapsulation barriers in comparison to BP nano-cage. Such as; the encapsulation barrier of F@AlP (7.57 kcal mol^-1) is lower than that of F@BP (129.78 kcal mol^-1). Moreover, distortion of nano-cages due to translation of elements is also estimated by distortion energies. Large distortion energies of 113.81/118.39 kcal mol^-1 are noticed for exo-B@AlP/exo-C@BP complexes. In addition, the electronic properties for all the complexes are probed and depicted that the endohedral doping have remarkable influence on the electronic properties of the nanocage in comparison to exohedral doping. NBO charge analysis shows that Be metal delivers charges of 0.08 |e|/0.03 |e| to the AlP/BP nanocage, causing the later more electron rich. Contrary to Be, all other doped atoms show negative charges.