Theoretical study on the interaction of neutral and charged Ti_n (n = 1-7) clusters with one oxygen molecule

摘要

The interactions between the neutral and charged (-2, -1, +1, and +2) Ti_n (n = 1-7) clusters and one O_2 molecule were investigated by density functional theory. The calculated results show that the oxygen molecule is dissociative on the neutral Ti_n clusters. Geometrically, the two O atoms are distributed at the two sides across the neutral Ti_n cluster for n = 1-4 and the oxygen atom favors the three-fold hollow site for n = 5, 6, and 7. The binding energy per atom (E _b) and energy gap (E_(gap)) show higher stability and lower chemical activity of the neutral Ti_nO_2 (n = 1-7) systems compared with the corresponding Ti_n clusters. The adsorption energies (E_(ad)) exhibit a continuously ascending tendency except for n = 4. The results of the addition of different charges (-2, -1, +1, and +2) on the most stable neutral Ti_nO2 (n = 1-7) systems indicate that their geometries are usually perturbed. The stabilities of the neutral Ti _nO2 systems are enhanced by adding one negative charge. The strongest interaction of the charged Ti_n clusters (-2, -1, +1, and +2) with O_2 molecule is found at charge +2.