The resulting structures of three BP polymorphs shown in Figs. ) exhibit tetrahedral stacking like that of diamond and dense polymorphs of BN. It should be noted that the structure of rhombohedral BP can be considered as three-dimensional (3D) form of a 2D analogue with 3 B-P layers shown in Fig. . The similar 2D structure has been considered earlier for the study of rh-B 2 N 2 , a new rhombohedral polymorph of boron nitride . However, the two-dimensional rh-BP is found less cohesive than the 3D rh-BP as shown in the last line of Table .