Parameterized absorptive electron scattering factors [Supplementary Material]

The transfer of electron flux from Bragg spots to diffuse scatter is modelled using complex scattering factors f + if′ in the Bloch wave methodology. In a two-beam Einstein model the imaginary `absorptive' scattering factor f′ can be obtained by the evaluation of an integral containing f over all possible scattering angles.

While more sophisticated models of diffuse scatter are widely used in the electron microscopy community, it is argued in this paper that this simple model is appropriate for current structure solution and refinement methods. The two-beam model is a straightforward numerical calculation, but even this simplistic approach can become time consuming for simulations of materials with large numbers of atoms in the unit cell and/or many incident beam orientations.