Al:
  lattice: cF
  mechanical:
    elastic:
      type: Hooke
      references:
        - J. Vallin et al.,
          Journal of Applied Physics 35(6), 1825-1826, 1964,
          10.1063/1.1713749
      C_11: 107.3e9
      C_12: 60.8e9
      C_44: 28.3e9