JECP/ED — A computer program for simulation of selected-area and precession electron diffraction patterns

Crystal structure determination by electron crystallography has been very successful in many fields, ranging from organic to inorganic materials. Collection of electron diffraction data is still a crucial step in electron crystallography. The curvature of the Ewald sphere limits the data available in each electron diffraction pattern. The dynamical multi-scattering effect of electron diffraction increases the complexity of the structure determination procedure. A precession method (Vincent & Midgley, 1994) has been used to solve the crystal structure of AlmFe by Gjonnes and coworker (Berg et al., 1998; Gjonnes et al., 1998). The advantages of precession electron diffraction are (i) the effective reduction of the dynamical multi-scattering effects, (ii) an increase in the amount of electron diffraction data due to the precession of the electron beam, (iii) the ability to obtain integrated intensity of each electron diffraction spot. In the present work, an electron diffraction simulation program, JECP/ED, is reported. The program can be used as a teaching aid for students as well as a tool for scientists working on electron diffraction experiments