EMZAgeom

Program: EMZAgeom

This is a very simple utility program that shows what the horizontal direction in a diffraction pattern will be for a given zone axis and crystal structure. All EMsoft programs follow the same convention.

To determine how the diffraction pattern will be oriented for the Aluminum structure and the [111] zone axis orientation, simply run the program on the command line and enter Al.xtal for the xtal file name prompt and 1,1,1 for the zone axis indices prompt. The program will be then produce the following output:

 Zone Axis :[  1  1  1]

 Crystal point group           :  m-3m
 Crystal point group number    : 32
 Laue group                    :  m-3m
 Diffraction group             : 6RmmR
 Diffraction group number      : 24
 Projection diffraction group  : 6mm1R

 Bright Field symmetry         :    3m1
 Whole Pattern symmetry        :    3m1
 Dark Field general symmetry   :     1
 Dark Field special symmetry   :     m

 Reciprocal lattice vectors : 
    (  0 -1  1) and (  1  0 -1)

 --> Note that the first of these vectors is by 
     default the horizontal direction in
     any diffraction pattern or image simulation. 
     All reference frames are right-handed.

So, for this zone axis direction, all EMsoft programs will have the reciprocal lattice vector (0 -1 1) pointing towards the right on every diffraction pattern (zone axis, CBED, etc) and image simulation. The other information listed shows the various symmetries to be expected for diffraction patterns.