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At the generalized gradient approximation (GGA), the elastic constants of the orthorhombic phase of NH 3 BH 3 were calculated with plane-wave pseudo-potential method. Our calculation showed that the orthorhombic phase NH 3 BH 3 is a loose and brittle material, as well as hard to be deformed, also we calculated the elastic anisotropies and the Debye temperatures from the elastic constants. And from the band structure and density of state (DOS), we concluded that NH 3 BH 3 is a wide-gap semiconductor and the band gap is almost 6.0 eV. The bonds between N atoms and H atoms show a strong covalent characteristic, B atoms and H atoms form ironic bonds, and so as to the B–N bonds. Electrons from the B atoms are absorbed by the H atoms around the B atoms, and the H atoms display electronegativity.

Various structural possibilities for binary alloy Ni n Al + ( n = 1–8) cationic isomers have been investigated using density functional method (BPW91) with the effective core potential LanL2DZ basis set. Our calculations predicted the existence of a number of previously unknown isomers. The charged-induced structural changes in these cations have been discussed. With Ni n +1 forming base, replacing a Ni atom at marginal positions by an Al atom would be helpful to find the stable structures of Ni n Al + cationic clusters and neutral Ni n Al clusters quickly and correctly. The resulting geometries show that the aluminum atom remains on the surface of the clusters. Moreover, the obtained clusters prefer to adopt three-dimensional (3D) structures at the smaller number of nickel atoms compared with the pure Ni n +1 clusters ( n ⩾ 3), the tetragonal and pentagonal configurations are favored energetically when n > 5. The most stable structures of Ni n Al + clusters are same as the neutral ones except n = 7. The analysis of stabilization energies reveals that Ni 5 Al and Ni 4 Al + clusters are the relatively most stable in this series.