Stability and Growth Modes of Ni--C Clusters: A Study based on All-Electron Density Function Theory

Growth modes of the free-standing NiC_N (N\le 8) and Ni₂C_N (N\le 8) clusters are investigated by the all-electron density functional theory. The results reveal that there are two competing modes for the growth of these clusters: the linear chain and the ring structure without transannular bonds. The lowest-energy geometries of NiC_N (N\le 8) are the linear chains with the Ni atom at one end, except for NiC₂ and NiC₇. The Ni₂C_N (N\le 8) clusters all
prefer to the linear chains with the two Ni atoms at the two ends. Mulliken population analysis indicates that the total spin of the lowest-energy cluster show significant odd--even alternation. The Ni_MC_N (M=1,2) clusters with the even N are one and those with the odd-N are zero.