Ordered binary crystal phases of Lennard-Jones mixtures

The lattice energies at zero temperature are calculated, using Lennard-Jones interactions, for a large number of crystal structures associated with ordered binary compounds. In units of the AA interaction length and strength (i.e., sigmaAA= epsilonAA= 1.0) we examine the lowest energy structures, including coexisting phases, across the space of cross-species interactions 0.6< or = sigmaAB< or = 1.1 and 1.0< or = epsilonAB< or = 2.0. The remaining parameters sigmaBB= 0.88 and epsilonBB= 0.5 are chosen so that the parameter space studied includes the space of binary glass-forming alloys. In addition to some large unit cell structures such as Ni3P and PuBr3 appearing among the lowest lattice energies, a number of low-energy structures based on close-packed lattices are found that do not correspond to any experimentally observed crystals. The prevalence and stability of metastable crystal phases at the compositions AB, A2B, and A3B is examined.