**************************** Theory Level ****************************
Input: [TheoryLevel = kohn_sham]

Exchange-correlation:
  Exchange
    Slater exchange (LDA)
    [1] P. A. M. Dirac, Math. Proc. Cambridge Philos. Soc. 26, 376 (1930)
    [2] F. Bloch, Z. Phys. 57, 545 (1929)
  Correlation
    Perdew & Zunger (Modified) (LDA)
    [1] J. P. Perdew and A. Zunger, Phys. Rev. B 23, 5048 (1981), modified to improve the matching between the low- and high-rs parts

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