On the behavior of single-particle dynamic properties of liquid Hg and other metals.

Recent experiments and classical molecular dynamics simulations performed on liquid Hg near melting have suggested the existence of two processes with different time scales in its single-particle dynamics. We report a study of this system by using ab initio molecular dynamics simulations, which recover the same kind of behavior, and we analyze it in terms of a theoretical approach, which clarifies its origin. We show that the previous interpretation has been induced by the unphysical extension of the diffusive model to short times. Moreover, we also find that quite different liquid metals, such as Si and Mg, also exhibit a similar behavior as Hg, with the only difference being in the time scales involved due to the different masses and interactions.