Molecular-dynamics simulations of amorphous Si

A new procedure for generating networks of Si atoms with the properties of amorphous Si is presented. We have used ab initio molecular-dynamics simulations and a simple simulation procedure to produce cells with radial distribution functions, coordination defect concentrations, and vibrational densities of states in excellent agreement with experiment. A comparison of our method is made with other techniques and the conditions under which specific kinds of defects occur in simulations (e.g., floating or dangling bonds) is discussed. Implications to calculations using semiempirical angle-dependent potentials is briefly discussed. We have found that Brillouin-zone sampling significantly affects interatomic forces, and that the final amorphous structures obtained are dependent upon the sampling scheme used.