type: Hooke

references:
  - F.H. Featherston and J.R. Nieghbours,
    Physical Review 130(4):1324-1333,
    https://doi.org/10.1103/PhysRev.130.1324,
    fit to Tab. III (T_min=100K, T_max=300K)

C_11: 523.6e+9
C_11,T: -7.607e+7
C_11,T^2: -1.551e+5

C_12: 205.1e+9
C_12,T: -2.843e+6

C_44: 160.8e+9
C_44,T: -1.057e+7
C_44,T^2: 9.933e+3

T_ref: 293.15