Hourglass Zoning
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EXAMP10
This illustrates exponential growth rates in section. Enter a simple crystal with MMM symmetry, orthorhombic, A, B and C axes of length one, and forms 100, 010 and 001, all with central distance one. Remove the orthographic rotation, if present.

Now select Sections/Growth Zones from the Input1 menu. Click on the Growth Zones radio button, and then on the Zone Settings button. In the Growth-Zone Settings dialog, click on the Exponential button. In the Non-linear group, the Total time should be 1.0 and the Interval 0.1.

Now click on the Rate Constants button. This brings up the Forms List... dialog - you must set or reset the rate constants for each of the forms listed.

The equations for all three forms by default have non-zero a coefficients only for the first term, giving constant rates. Leave the first two forms alone, and select the third form, 001. Set a1 to 0.75 and a2 to 2.0. This gives a dependence on time to the power one, since b2 is one by default.

Remove the dialogs by clicking on OK, then select Display from the Modes menu, and set the display mode to Sections/Zones. The drawing will be replotted automatically. On the first calculation, the plot will probably go off-scale; simply select Replot from the Display menu and the results of the first plot will be used to scale the second.