Pressure-induced structural change of liquid carbon: Ab initio molecular-dynamics simulations

We have studied the pressure-induced structural change of liquid carbon using ab initio molecular-dynamics simulations. When the temperature is increased at a constant density of 2.9 g/cm3, the structural change is not qualitative but quantitative and the average coordination number is almost unchanged. When the pressure is increased at a constant temperature of 9000 K, the structure changes drastically; the peaks of g(r) shift to shorter distances and become higher and sharper, and the average coordination number increases. The S(k) changes its shape qualitatively at extremely high pressure and becomes similar to those of liquid Si and Ge at ambient pressure.