INDXPAT can be used to refine the cell parameters, crystal orientation,
beam center and crystal-detector distance. The volume of the cell can
not be refined and will be kept constant. The program works with a stack
of parameters to be refined. It starts with an empty stack.
To add a (group of) parameter(s), use one or
more of the following commands:
fit cell
fit orientation
fit beam
fit distance
To remove a (group of) parameter(s) from the list
of parameters to be refined or to fix all paramaters,
use one or more of the following commands:
fix cell
fix orientation
fix beam
fix distance
fix all
The refinement is done for a number of cycles that has to be specified
by the user. If convergence is achieved before the specified number
of cycles were run, the program will stop automatically.
gogo 100
After each refinement step, the program will list the changes in the
values of the parameters, like:
Refinement converged after 6 cycles.
cell 26.336 26.393 26.544 60.24 60.10 59.93
shifts 0.000 -0.018 -0.043 0.02 0.14 0.14
est. errors 0.018 0.015 0.014 0.043 0.034 0.038
orientation -160.044 -42.609 -29.753
shifts 0.103 -0.141 -0.127
est. errors 0.045 0.026 0.028
origin shift -0.025 0.092 shifts -0.025 0.092 calc.errors 0.178 0.197
cfdistance 81.98 shift -0.02 calc.errors 0.34
Number of observed spots used in the refinement: 1000 (out of 1269).
Root mean square distance between predicted and observed spots: 0.265572 (mm).
Check the root-mean-square distance between the predicted and observed spot
positions.
The observed spots should be reindexed explicitely after each
step of refinement by running INDXPAT:
run INDXPAT
If more spots were indexed and the root-mean-square value goes up again,
the refinement should be continued.
If the patterns does not fit well enough, adjust the value of
dmin. This parameter gives the mimimum distance between
an observed and a predicted spot position for a spot to be considered as
indexed.
dmin 0.6