Potential energy surfaces (PES) of Co clusters with Gupta potential using four parameter sets are characterized in terms of conformational analysis. Their structures are obtained using three optimization algorithms. Three new structures with lower energies for one of these parameter sets are found. For all parameter sets, the structural variation from icosahedron to decahedron to close-packed face centered cubic (FCC) or stacking fault FCC and amorphous motifs is related to the potential range of the parameters. The difference between the PES is investigated, and for a long potential-range parameter, the number of local minima on the PES is extremely large. (C) 2016 Elsevier B.V. All rights reserved.