Structural Stability and Cohesive Energy

The structural features and cohesive energy of Molybdenum (Mo) and Tungsten (W) spherical metallic nanocrystals are investigated by energy minimization method at 0 K. Three different models for the potential energy function are proposed. The first is Erkoc potential energy function. The work on this potential is divided into two parts. A) The first was devoted to the two-body part. B) The second works on the full Erkoc Potential energy function. Both models had good agreement with previous works that used other models for BCC and FCC crystal structures. The size dependence of the cohesive energy was predicted by both potentials. The results of model (A) worked for BCC and FCC were in excellent agreement with the experimental measurements of Mo and W. According to model (B), nanocrystals composed of 2000 atoms have an energy ratio of 0.56 and 0.58 for Mo and W respectively. The third model proposed is a potential function comprising two and three body terms as Mie-type (m = 8, k = 4) and Teller-Axilord potentials respectively. This model has been used and proves to fit excellently with experimental data.