Universal Algorithm for Reconstruction of Atomic Models of Noncrystalline Systems

Abstract

A new algorithm is suggested for constructing models of noncrystalline substances from a known pair correlation function (PCF). The algorithm allows the models to be reconstructed for any temperature, including the vicinity of absolute zero. The algorithm compares the coordination numbers of the target and model PCFs for all distances of the PCF histogram. The coordination number comparison algorithm includes calculating, in each iteration, a correction to the pair force function and ensures the convergence of the process to the sought force function at which the PCF of the molecular dynamic (or static) model practically coincides with the target PCF. The algorithm makes it possible to attain a very small standard deviation of the model PCF from the target PCF (~0.01) at which the plots of the two functions are visually indistinguishable. Reconstructed force functions usually differ from the functions used in the construction of target models. This indicates nonuniqueness of the solution of the inverse problem of modeling.