Linear scaling nonorthogonal tight-binding molecular dynamics for nonperiodic systems

I present a method for efficiently calculating atomic forces from nonorthog onal tight-binding models. This method is applicable to systems that cannot be described by a periodic supercell. I use the method to determine the te mperature-dependent structure of a silicon screw dislocation core. The core reconstruction changes with temperature; a broad, disordered core with man y coordination defects appears at high temperatures.