MODIFICATION OF THE MULTISLICE METHOD FOR CALCULATING COHERENT STEM IMAGES

Based on the Schrodinger equation, the multislice method is derived in a new way which is more appropriate for calculating coherent STEM ima ges. It is shown that the effects of beam tilt can be included in two equivalent ways which are convenient for different purposes of applica tion. It is shown that, if the coherent STEM probe is considered as a superposition of many tilted plane waves, one cannot use the tradition al multislice formulae for each tilted beam, since this leads to the l oss of phase information which can be important for coherent many-beam illumination. The new formulations lead to a faster procedure for coh erent STEM image simulations. Advantages of the proposed procedure are discussed with respect to a few different illumination conditions.