Eval15 Xtal description

Create the xtal

4 ways to build a xtal model:
  1. use the model command
    You can use one of the five built-in models using the model command. The dimensions of the models can be changed with xa, xb and xc. The overall dimensions can be changed with xtalscale.
  2. read a list of corner coordinates
    Use the readcorners command to read a file with corner coordinates (in the laboratory system). If a rmatfile with the same name as the cornerfile is found, the orientation matrix from that rmat file will be used. The value of xtalscale will not be used.
  3. read a list of face indices
    Use the readins command to read a absorb.ins-like file with cell parameters and face indices. If an rmatfile with the same name as the facesfile is found, the orientation matrix from the rmat file will be used. The value of xtalscale will not be used.
  4. read a xtal.evc file
    Use the loadxtalevc command to read an evalccd input file. The relevant items read from the file are:

Orientation matrix

To calculate face indices, an orientation matrix is needed. You can read an orientation matrix with the rmat command. If you use boxopen to read a boxfile, the orientation matrix is extracted from the boxfile.
If no orientation matrix is present, it will be build using the cell parameters (as specified with the cell command; the default cell parameters are 10,10,10,90,90,90).

Orientation of the xtal

The orientation of the xtal can be changed with the
  1. There are 3 angles to set the xtal orientation with respect to the goniometer head. They describe the rotatations on the xtal to align the xtal edges (as defined by xa, xb and xc) with the laboratory system. The reversed rotations in reversed order are used to calculate to actual orientation of the xtal.
    These rotations are only used in combination with the model command (so they are not used by the commands readins and readcorners).
    Use the loadxtalevc command to read an evalccd input file. The orient record in this file will sets xrotx, xroty and xrotz.
  2. An arbitrary rotation can be applied with the xrot command. This will rotate xtal corners and faces around the axis defined with xtalax.
    Note: this is still with respect to the goniometer head.
  3. The position of the goniometer head on the goniostat is set with goniostat.


During a animate the orientation of the xtal will be changed if randomorient=on.

Xtal Sampling

The xtal needs to be sampled for a simulation (simulate > 0). The sample size is set with the xtalsample command. The number of sample points is limited to 500,000. The sample list will be (re)build after a change in the xtal model (i.e. after one of the commands: menu, loadxtalevc, model, readcorners, readins, xa, xb, xc or xtalscale) or after a new value for xtalsample.

Examples

3 ways of creating a 0.3 mm cube.
  1. xa 0.3 xb 0.3 xc 0.3 xtalscale 1.0 model 2
    or assuming the default value 0.2 for xa, xb and xc: xtalscale 1.5 model 2
  2. create a file cube.xyz
     0.15  0.15  0.15
-0.15  0.15  0.15
-0.15 -0.15  0.15
 0.15 -0.15  0.15
 0.15  0.15 -0.15
-0.15  0.15 -0.15
-0.15 -0.15 -0.15
 0.15 -0.15 -0.15

    readcorners cube
  3. create a file cube.ins
    TITL cube
CELL 0.71073 10 10 10 90 90 90
FACE  1  0  0 0.15
FACE -1  0  0 0.15
FACE  0  1  0 0.15
FACE  0 -1  0 0.15
FACE  0  0  1 0.15
FACE  0  0 -1 0.15

    readins cube
Eval15
Eval15 commands