Abstract:The super-cell system of Ti-doped VH2 was optimized by means of plane-wave pseudopotential, employing the first-principle of density functional theory (DFT). The results show that the cell parameters of V1-xTixH2 and total energy of the system increase gradually with the increment of Ti, so the stability of the system decreases and the capability of releasing hydrogen is improved. The density of states, net charge, bond order and electronic density of V1-xTixH2 (x = 0, 0.13, 0.30, 0.48, 0.65, 1) were also computed and analyzed. The calculation results show that the net charge of V increases whereas that of H decreases gradually with the increment of Ti; the ionic interaction between V-H is reinforced and at the same time the valent interaction is weakened; the bond order of V-H increases, the interaction between V and H becomes stronger, and thus the capability of absorbing hydrogen is improved by adding a certain amount of Ti to VH2. However, when the content of Ti in VH2 exceeds 0.48 (x>0.48), the bond order of V-H decreases, and the capability of absorbing hydrogen is decreased.