The V ( p ) equation of state obtained using single-crystal X-ray diffraction measurements (open circles) is well accounted for by a third-order BirchMurnaghan fit (solid line). The errors for p and V are given for the uncertainties in the measurement as described in Methods . The low-pressure behaviour obtained from DFT-driven geometry optimizations of a 2 x 2 x 2 approximant is shown as open squares and that of our coarse-grained lattice-dynamical models (CG model) is shown as a shaded region.
