that neighboring Bi displacements show some correlation with each other, with a preference for phi = 180 ◦ align- ment. This corresponds to a zig-zag type ordering that merits further investigation. Measures of the tetrahedric- ity S ( T$_{d}$ ) of the O $^{′}$Bi$_{4}$ sublattice indicate that neighbor- ing displacements are weakly correlated, thus the sublat- tice may exhibit some rigidity. M. G. Tucker, and A. L. Goodwin for helpful discus- sions. This work was supported by the Institute for Mul- tiscale Materials Studies and the National Science Foun- dation through a Career Award (DMR 0449354) to RS and MRSEC facilities (DMR 0520415). Neutron scatter- ing was performed on NPDF at the Lujan Center at the Los Alamos Neutron Science Center, funded by the DOE Office of Basic Energy Sciences. Los Alamos National Laboratory is operated by Los Alamos National Security, LLC under DOE Contract DE-AC52-06NA25396. We thank M. Pinsky and D. Avnir for providing the CSM script, and we thank K. 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