Convergence properties of X-ray scattering calculated from protein crystal molecular dynamics simulations

A fundamental question when comparing molecular dynamics computer simulations of proteins with scattering experiments is how the convergence of the scattered intensity depends on simulation length. Here results are presented of a molecular dynamics simulation of crystalline Staphylococcal nuclease that is analyzed in terms of the displacement correlation matrix and the X-ray diffuse scattering pattern. The convergence of these quantities is compared to the spatial separation of the atoms involved. On the nanosecond timescale the correlation matrix converges for atom pairs with a separation ≤ 5 Angst