Fast calculation of diffraction patterns from an ensemble of aligned molecules
Phys. Rev. A 112, 012813 – Published 17 July, 2025
DOI: https://doi.org/10.1103/bz9z-btdv
Abstract
We report an algorithm to calculate electron diffraction patterns for molecules with anisotropic angular distribution, which is significantly faster than existing methods. The algorithm uses a transform to convert the molecular orientation distribution, which is a function of three Euler angles, to the atom-pair distribution functions which depend on the polar and azimuthal angles. The diffraction signal can then be calculated from the atom-pair distributions. We demonstrate the computation method numerically by calculating electron diffraction patterns for a symmetric top molecule (trifluoroiodomethane) and an asymmetric top molecule (formaldehyde) and show that it reduces the calculation time by approximately two orders of magnitude compared to the standard brute-force method. The method can also be applied to the calculation of x-ray diffraction patterns.
