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There are several open questions. What is the effect of U on the energy landscape. Does U simply shift the local minima relative to one another, or does it create and destroy minima? Additionally, when is U necessary for correct reordering of the candidate energies? Perhaps U is only necessary for compound containing correlated atoms, or magnetic materials. Larger scale studies on multiple keystone compositions is necessary.  In conclusion, our proposed strategy for structural prediction is as follows: first perform USPEX runs with spin-polarized DFT to generate the list of structures occupying local minima in the energy landscape. Then, apply LDA+U to the resulting structures to reorder the total energies to determine the true ground state structure. This is more economical than running USPEX with hundreds of calls to LDA+U, since LDA+U is more expensive than LDA. [Ran, could you estimate the difference in running time between your proposed re-ordering algorithm vs. the naive USPEX LDA+U run?]  \emph{Global stability} -- Since the material was known to exist, we We  did not construct the convex hull and check for global thermodynamic stability. [Maybe stability as the material was known to exist. [Perhaps  we should do this. What do you think, Gabi?] should.]  Our proposed algorithm for structure prediction generates several novel questions. How does $U$ affect the energy landscape? In particular, does $U$ simply shift the local minima relative to one another, or does it create and destroy minima? Additionally, when is $U$ necessary for correct reordering of the candidate energies? We expect that $U$ is only necessary for compounds containing atoms with partially-filled $d$ or $f$ shells or magnetic materials, and this hypothesis deserves to be investigated.