EFFICIENT BEAM-SELECTION CRITERIA IN QUANTITATIVE CONVERGENT-BEAM ELECTRON-DIFFRACTION

New criteria to identify significant beams in many beam dynamical calc ulations are introduced. The new beam selection criteria are used in a structure factor refinement procedure where the correct identificatio n of the most significant beams is crucial. Beams are divided into two categories. Strong beams are included in the dynamical calculations t hrough diagonalisation. The effects of weak beams are successfully des cribed by Bethe-perturbation of the dynamical matrix. The new method i s compared to existing algorithms and found favourable, both in terms of computing time and stability in calculations.