Electronic and atomic structures of supercritical fluid selenium: ab initio molecular dynamics simulations

Abstract The electronic and atomic structures of supercritical fluid selenium are investigated by means of ab initio molecular dynamics simulations using the fully-spin-polarized and generalized-gradient-corrected density functional theory. It is shown that the calculated structure factors are in good agreement with recent X-ray diffraction experiments over a wide range of temperature and pressure. It is demonstrated how fluid Se changes from the chain structure to an assembly of Se 2 dimers with decreasing density in the supercritical region. The relation between the structural change and the spatial distribution of the spin density is discussed.