Dynamical properties of liquid phosphorus studied by ab initio molecular-dynamics simulations

We have performed ab initio molecular-dynamics simulations for the low-density and high-density liquid phosphorus to investigate their dynamical properties. We have shown that: (i) The vibration modes within the tetrahedral P4 molecules in the low-density molecular liquid can be seen in the calculated velocity autocorrelation function and its spectrum. (ii) A so-called de Gennes narrowing due to the strong spatial correlation between the P4 molecules and phonon peaks are seen in the calculated dynamic structure factors. (iii) The sound velocities estimated from the dispersion relation obtained from the dynamic structure factors are 2100 m s−1 for the molecular liquid and 5300 m s−1 for the polymeric liquid, which reflect the differences in the density and in the liquid state.