The particle scattering factor of branched macromolecules: computer simulation

Abstract

Theoretical prediction of the particle scattering factor I (ϑ) is possible for a limited number of molecular shapes (random coils, spheres, cylinders), which can be described in terms of distances only. Given the importance of branched macromolecules, where angles also play a role, we have devised a computer procedure for calculating the particle scattering factor. Scattering was simulated for trees with alternate and with opposite branches, with straight branches and with broken branches, 2-dimensional as well as 3-dimensional, and also for systems consisting of two trees acting as a single scatterer. To elucidate various factors affecting I (ϑ), several parameters were varied, including angles between trunks and branches, angles between two linear fragments of a broken branch, and densities of linear fragments. Light scattering by generalized trees consisting of unconnected segments has been discussed. For normal trees representing real molecules, procedures enabling considerable savings in computing times have been devised.