Force-enhanced atomic refinement: Structural modeling with interatomic forces in a reverse Monte Carlo approach applied to amorphous Si andSiO2

Abstract

We introduce a structural modeling technique, called force-enhanced atomic refinement (FEAR). The technique incorporates interatomic forces in reverse Monte Carlo (RMC) simulations for structural refinement by fitting experimental diffraction data using the conventional RMC algorithm, and minimizes the total energy and forces from an interatomic potential. We illustrate the usefulness of the approach by studying $a\text{\ensuremath{-}}{\text{SiO}}_{2}$ and $a\text{\ensuremath{-}}\text{Si}$. The structural and electronic properties of the FEAR models agree well with experimental neutron and x-ray diffraction data and the results obtained from previous molecular dynamics simulations of $a\text{\ensuremath{-}}{\text{SiO}}_{2}$ and $a\text{\ensuremath{-}}\text{Si}$. We have shown that the method is more efficient than the conventional molecular dynamics simulations via ``melt quench.'' The computational time in FEAR has been observed to scale quadratically with the number of atoms.