Structure and electron-ion correlation of liquid germanium

Structure factor of liquid germanium (Ge) has a shoulder at θ = 3.2 Å−1 in the high-momentum-transfer region of the first peak. To investigate the origin of such a non-simplicity in the structure, high energy X-ray diffraction measurements have been performed using 113.26 keV incident X-ray, at BL04B2 beamline of SPring-8. By a combination of the obtained structure factor with the reported neutron diffraction data, charge density function and electron-ion partial structure factor have been deduced. The peak position of the charge distribution is located at about 1 Å, rather smaller r value than the half value of nearest neighbor distance (∼2.7 Å), which suggests that valence electrons of liquid Ge play a role of screening electrons around a metallic ion rather than covalently bonding electrons.