Figure 3

(a) Evolution of the Ge-Se interatomic distance as a function of increasing pressure. The filled symbols represent Ge₁₇Se₈₃ (black) and Ge₂₀Se₈₀ (red). The open diamond symbols are AIMD results for Ge₁₈Se₈₂. The estimated error bars are shown separately in the graph. The red dashed line corresponds to the interception of low and high pressure regimes shown by the pressure dependence of the PP position in Fig. 1b. (b) Energy decrease in the Ge K absorption edge position with increasing pressure of Ge₁₇Se₈₃. In the inset, the XANES spectra of selected pressures are compared to illustrate the edge shift.