Crystalline and amorphous nanostructures in porous silicon

We report ab initio molecular dynamic simulations of several supercells of crystalline porous silicon, that are first relaxed and then analyzed by their radial distribution functions (RDF). The porosities vary from 10% to 80% of the total volume of the supercell. The interatomic distance is determined by the position of the first peak of the RDF. We manipulated a maximum of 500 atoms of silicon and a minimum of 32. The interatomic distance of the model with a porosity of 10% was 2.35 A, for those models with porosity from 11% to 50% was 2.45 A and finally, 2.55 A for those with a porosity greater than 50%. If the supercell backbone structure is small compared with the void of the supercell, then the interatomic distance between the silicon atoms run out of the crystalline value. Our results agree with experiment.