Molecular dynamics simulations of a large structure of amorphous Si and direct calculations of the structure factor

There have been a number of simulations of fully bonded models of a-Si containing of the order of 10 2 atoms; comparison was then made with the pair distribution function deduced from neutron and X-ray scattering measurements on Si (or Ge). Obtaining the pair distribution function from the primary data produces a convoluted pair distribution function, and it seems sensible to compute the structure factor so as to make possible a direct comparison with experiment. The authors have taken the basic model of Wooten, Winer and Weaire and relaxed it slightly to conform the Stillinger-Weber potential. This is a periodic structure but they have put together 64 such blocks, heated them rapidly to remove the periodicity, then coded them rapidly to 0 K. The resulting structure factors agree extremely well with experimental measurements.