Liquid-liquid Phase transitions in silicon

Abstract

We use computationally simple neutral pseudo-atom ('average atom' or 'single-center') density functional theory (DFT) as well as standard N-atom DFT to elucidate liquid-liquid phase transitions (LPTs) in supercooled liquid silicon at 1200K, as well as in silicon as 'warm dense matter' at 11604K (1 eV). An ionization-driven transition and three LPTs including the known LPT near 2.5 g/cm 3 are found. They are robust even to 1 eV. The pair distributions functions, pair potentials, electrical conductivities, and compressibilites are reported. The origin of the LPTs are clarified within a Fermi liquid picture of strong electron-ion scattering at the Fermi energy and complements the commonly used transient covalent bonding picture.