Where gij is the radial distribution function between species i and j. The major contribution in this integral comes from distances r < 1.0 -1.5 nm. Here we have chosen the upper limit r =1.2 nm for getting the Gij values. A positive value of Gij indicates that the number of particle type j around i type particle is greater than the number of j type particle present in the bulk where particle type i is absent at the center in the same volume element.