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., sigma(AA)=epsilon(AA)=1.0) we examine the lowest energy structures, including coexisting phases, across the space of cross-species interactions 0.6less than or equal tosigma(AB)less than or equal to1.1 and 1.0less than or equal toepsilon(AB)less than or equal to2.0. The remaining parameters sigma(BB)=0.88 and epsilon(BB)=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, A(2)B, and A(3)B is examined. (C) 2004 American Institute of Physics.