Un estudio comparativo ab initio de la dinámica colectiva en aleaciones líquidas Al90Si10 y Al90Mg10

Dispersion of acoustic and optic collective excitations are comparatively studied in two Al-based liquid metallic alloys, which contain ten atomic percent of Si with four valence electrons or Mg with two ones. Partial density-density and current-current time correlation functions are analyzed by a combination of {\it ab initio} molecular dynamics simulations and theoretical generalized collective modes (GCM) approach. We obtain and analyze the dispersion of acoustic and optic collective excitations and wave number dependence of the slowest relaxation process as eigenmodes of the generalized Langevin equation in matrix form. These findings allow understanding of different factors responsible for features in collective dynamics of these two liquid metallic alloys.