First-principles molecular-dynamics simulation of liquid rubidium under high pressures

The effects of compression on the structural and electronic properties of liquid rubidium are studied along the melting curve by means of a first-principles molecular-dynamics simulation. It is shown that the calculated pair distribution functions g(r) are in good agreement with the experimental results for a wide range of pressures; the liquid rubidium is compressed uniformly at 2.5 GPa, and there exist some deviations from the uniform compression at 6.1 GPa. This structural change to a denser state is related to an electronic s-d transition in the liquid state. It is found that, near the triple point, the electronic density of states consists mostly of the s component and, with increasing pressure, the s component decreases gradually over a wide range of energy, and the d component near the Fermi level increases.