Methodology:
Geometry optimization and normal mode frequency calculation of CHD
monomer along with all the studied (CHD)n(n = 2-6) clusters were performed employing B3LYP functional in
conjunction with 6-311++g** basis set. For calculation of binding
energies of the clusters, basis set superposition errors (BSSE) were
corrected using the single point counterpoise method of Boys and
Bernardi59. Further,
counterpoise corrected single point energies for all the species were
calculated at M06-2X/6-311++g** level using the geometries optimized at
B3LYP/6-311++g** level. The total binding energy of a cluster comprising
of n monomeric CHDs is defined by equation. (1)