Molecular dynamics simulations were performed to study thermodynamics and structural properties of expanded fluid Cs. Internal pressure, radial distribution functions (RDFs), coordination numbers and diffusion coefficients have been calculated at temperature range 700-1600 K and pressure range 100-800 bar. We used internal pressure to predict the metalnonmetal transition occurrence region. RDFs were calculated at wide ranges of temperature and pressure. The oordination numbers decrease and positions of the first picks of RDFs slightly increase as the temperature increases and pressure decreases. The calculated self-diffusion coefficients at various temperatures and pressures show no distinct boundary between Cs metallic fluid and its expanded fluid where it continuously increases with temperature.
