Quantum chemical studies on the structural and electronic properties of nickel sulphide and iron sulphide nanoclusters

Nanoclusters of nickel sulphide (NiS)n and iron sulphide (FeS)n for n = 3–5 are studied using B3LYP exchange correlation function with 6-31G as a basis set. The structural stability of different isomers of NiS and FeS is analysed with the optimized energy, binding energy and vibrational studies. The electronic properties of isomers are discussed in terms of HOMO–LUMO gap, ionization potential, electron affinity, and embedding energy of different clusters. Based on the calculated energy, planar ring, linear ladder and bipyramidal cube of NiS and FeS nanoclusters are found to be more stable. The increase in number of atoms in the clusters leads to increase in its stability. The dipole moment is high for planar rhombus and linear ladder structures of NiS and FeS nanoclusters. The ionization potential and electron affinity are high for planar ring structure of NiS and FeS clusters. The value of energy gap of linear ladder NiS nanocluster and cube and bipyramidal cube structures of FeS is found to be low. The binding energy for cube structure of NiS and FeS clusters is found to be high. Hexagonal ring structure of NiS and FeS clusters has low embedding energy value. The other parameters such as dipole moment and point symmetry are also discussed. The structural stability and electronic properties will provide an insight for experimentalist to tailor new materials that have potential importance in engineering applications.