The concentration fluctuations and the mutual diffusion coefficient in the supercritical solution

Molecular dynamics simulations on Lennard-Jones mixture in the supercritical region are performed. The number of the molecules in the unit cell is 23328 and the mole fraction is 0.5. The concentration fluctuations near the critical point are large compared to the ideal mixing. The mutual diffusion coefficient normalized by the self-diffusion coefficient has a small value near the critical density because of the large concentration fluctuation. The heat capacity, partial molar volume and correlation lengths of density and concentration in the supercritical region are compared with those at the normal density.