Atomic layering at the liquid silicon surface: A first-principles simulation

We simulate the liquid silicon surface with first-principles molecular dyna mics in a slab geometry. We find that the atom-density profile presents a p ronounced layering, similar to those observed in low-temperature liquid met als like Ga and Hg. The depth-dependent pair correlation function shows tha t the effect originates from directional bonding of Si atoms at the surface , and propagates into the bulk. The layering has no major effects in the el ectronic and dynamical properties of the system, that are very similar to t hose of bull; liquid Si. To our knowledge, this is the first study of a liq uid surface by first-principles molecular dynamics. [S0163-1829(99)50648-6] .