This paper investigates the lowest-energy structures,stabilities and electronic properties of (BAs) n clusters (n=1-14) by means of the density-functional theory.The results show that the lowest-energy structures undergo a structural change from two-dimensional to three-dimensional when n=4.With the increase of the cluster size (n 6),the (BAs) n clusters tend to adopt cage-like structures,which can be considered as being built from B 2 As 2 and six-membered rings with B-As bond alternative arrangement.The binding energy per atom,second-order energy differences,vertical electron affinity and vertical ionization potential are calculated and discussed.The caculated HOMO-LUMO gaps reveal that the clusters have typical semiconductor characteristics.The analysis of partial density of states suggests that there are strong covalence and molecular characteristics in the clusters.
This paper studies the small molybdenum clusters of Mo n (n=2-8) and their adsorption of N2 molecule by using the density functional theory (DFT) with the generalized gradient approximation. The optimized structures of Mo n clusters show the onset of a structural transition from a close-packed structure towards a body-centred cubic structure occurred at n=7. An analysis of adsorption energies suggests that the Mo2 is of high inertness and Mo6 cluster is of high activity against the adsorption of N2 . Calculated results indicate that the N2 molecule prefers end-on mode by forming a linear or quasi-linear structure Mo-N-N, and the adsorption of nitrogen on molybdenum clusters is molecular adsorption with slightly elongated N-N bond. The electron density of highest occupied molecular orbital and lowest unoccupied molecular orbital, and the partial density of states of representative cluster are also used to characterize the adsorption properties of N2 on the sized Mon clusters.
The lowest-energy structures and the electronic properties of Mo2nNn(n=1-5) clusters have been studied by using the density functional theory(DFT) simulating package DMol 3 in the generalized gradient approximation(GGA).The resulting equilibrium geometries show that the lowest-energy structures are dominated by central cores which correspond to the ground states of Mo n(n = 2,4,6,8,10) clusters and nitrogen atoms which surround these cores.The average binding energy,the adiabatic electron affinity(AEA),the vertical electron affinity(VEA),the adiabatic ionization potential(AIP) and the vertical ionization potential(VIP) of Mo2nNn(n=1-5) clusters have been estimated.The HOMO-LUMO gaps reveal that the clusters have strong chemical activities.An analysis of Mulliken charge distribution shows that charge-transfer moves from Mo atoms to N atoms and increases with cluster size.
