Both ccp and hcp have identical close-packed volumes, but the calculated Gibbs free energy of the two arrangements shows that ccp is more stable by 0.002–0.012 kJ mol⁻¹ at room temperature (L.V. Woodcock, Nature, 1997, 385, 141, P.G. Bolhuis, D. Frenkel, S-C Mau and D.A. Huse, Nature, 1997, 388, 235). Determine independently the number of neighbours in the first five coordination shells for these two close-packed structures and, thereby, describe the origin of this difference in free energy.