Atomic topology and radial distribution functions of a-SiNx

We report a new approach to simulate amorphous networks of covalently bonded materials that leads to excellent radial distribution functions and realistic atomic arrangements. We apply it to generate the first ab initio structures of nitrogen-doped silicon, a-SiNx, for thirteen values of x from 0 to the nearly stoichiometric composition of x=1.29, using the Harris functional and thermally amorphizised, periodically continued, diamond-like cells with 64 atoms. Partial radial features are reported for the first time and the total radial distribution functions agree very well with the few existing experiments. Our results should stimulate further experimental and theoretical studies in amorphous covalent materials.