Determination of the Shape of a Helix Particle Based on Small-Angle X-ray Scattering Data: Modification of the "Simulated Annealing" Algorithm

The modified "simulated annealing" algorithm implemented in the DAMMINV software allows one to obtain 10 to 15 different nanoparticle models fitting small-angle X-ray scattering data. This method is based on the mode of intermittent weights of the objective function, which balances between minimization of the penalty coefficients, responsible for the model meaningfulness, and the discrepancy between the experimental and model scattering data. The effect of noise on the scattering curves on the quality of three-dimensional helix shape reconstruction has been investigated, and the results are compared with the data obtained using standard programs. The method has been verified on noise-free model data and data with superimposed Poisson noise by the example of a helix particle with a thickness of turns comparable to the characteristic size of the space between them. A comparative analysis of the reconstructed models and the three-dimensional shapes obtained using standard modes of the "simulated annealing" algorithm has been performed.