A theoretical study on the structures of phosphorus clusters P₁₂

Twenty-eight structures of P₁₂ were acquired with molecular graphics and optimizations were carried out with molecular mechanics, PM3 semi-empirical and ab initio calculations. In these structures, the phosphorus atoms could be two-fold, threefold or four-fold coordinated. The model of D_3d symmetry derived from condensing two cuneane P₈ via the sharing of four atoms is the most stable isomer. The imaging of enough cluster models can help to locate the global minimum. Many P₁₂ structures are characterized by atoms in three-fold mode and those that have atoms(s) in two-fold coordination have high energies. Both tetrahedral P₄ and cuneane P₈ are common components and could be important candidates for the construction of larger clusters. A planar pentagonal structure is more popular than a hexagonal one in phosphorus clusters.