ION-ELECTRON CORRELATIONS IN LIQUID-METALS FROM ORBITAL-FREE AB-INITIO MOLECULAR-DYNAMICS

Extensive ab initio molecular-dynamics (AIMD) simulations have been pe rformed for liquid Na, Mg, and Al, three metals having the same core o f 10 electrons but with a different number of valence electrons. The c alculations have been carried out with the orbital-free version of the Car-Parrinello technique. Results were obtained for the functions tha t describe the ion-ion and ion-electron correlations. Comparison of th ese with results of those from standard Kohn-Sham AIMD confirms the ab ility of the orbital-free scheme to provide correct properties from fi rst principles at a reasonable computational cost. The results present ed here demonstrate that the overall ion-electron correlations predict ed by simulation differ substantially from the experimental data so fa r reported for this property. This observation is closely related to t he fact that, according to the theory, the difference between x-ray an d neutron-diffraction structure factors should be much smaller than th at encountered in the experiments.