is dependent on the Euclidean inter-atomic distance between the two atom sites, denoted r 0Ii,lJj . The inter-atomic distance can be determined from the variables defining the geometry of the crystal (i.e., r 0Ii,lJj = r 0Ii,lJj (θ, Ω)). At relatively close ranges, the exponential contribution to the Buckingham potential dominates and accounts for repulsion forces arising from the Pauli-exclusion principle. This decays rapidly with inter-atomic distance and gives way to first-order long-range London dispersive forces that decay with the inter-atomic distance to the negative sixth power. The model contains three parameters per atom-atom interaction (A Ii,Jj , B Ii,Jj , C Ii,Jj ), influencing the shape and depth of the potential.