Fig. 7.

Crystal structure of SiH₄ at 72 GPa having P4/nbm symmetry. Si atoms (blue solid spheres) are surrounded by H atoms (pink solid spheres). H atoms outside of the unit cell (dashed lines) are included for clarity to show complete tetrahedra. We define d₁ (cyan bond) as the intradistance of a tetrahedron in the lower and upper hydrogen layer, d₂ (red bond) as the interdistance of two nearest tetrahedra, and d₃ (black bond) as the intradistance of a tetrahedron between two layers.