Create a dislocation dipole in a crystal.  The dislocation line and dipole
direction must be parallel to one of the repeat vectors of the simulation box.

<p>
Usage: <tt>input = [ <i>zind yind sbx sby sbz sx0 sy0 sy1 nu nimg_xmin nimg_xmax 
       nimg_ymin nimg_ymax tilt_box  limit_sz  sz_min sz_max store</i> ] 
       makedipole</tt>

<p>
<tt><i>zind</i></tt> = 1, 2 or 3 specifies the direction of the dislocation line
(to be parallel to <tt><b>c</b><sub>1</sub></tt>, <tt><b>c</b><sub>2</sub></tt>, 
or <tt><b>c</b><sub>3</sub></tt>).
<br>
<tt><i>yind</i></tt> = 1, 2 or 3 specifies the direction of the dislocation
dipole (also the direction that contains the cut plane of the dislocation).
<br>
<tt><i>sbx, sby, sbz</i></tt> specify the Burgers vector in <b>scaled</b> coordinates.
<br>
<tt><i>sx0, sy0</i></tt> specify the location of one dislocation in scaled coordinates,
<tt><i>sy1</i></tt> specifies the location of the other dislocation.
<br>
<tt><i>nu</i></tt> is the Poisson's ratio of the crystal, needed in the expression 
 for the displacement field of non-screw dislocations.  
<tt>nu</tt> is usually set to be 0.3.  
<br>
<tt><i>nimg_xmin, nimg_xmax, nimg_ymin, nimg_ymax</i></tt> specify the number of 
periodic images to be summed to obtain a periodic solution.  They are commonly set to be
<tt>-10 10 -10 10</tt>.
<br>
If <tt><i>tilt_box</i> = 1</tt>, then the box <b>H</b> is allowed to tilt to accommodate
the plastic strain produced by the dislocation dipole.  If <tt><i>tilt_box</i> = 0</tt>,
then the box <b>H</b> is fixed, and there will be an (usually huge) internal stress
inside the simulation box.
<br>
If <tt><i>limit_sz</i> = 1</tt>, then this operation is only performed for atoms 
whose <tt><i>zind</i></tt>-th scaled coordinate lies between <tt>szmin</tt> and 
<tt>szmax</tt>.
<br>
If <tt><i>store</i> = 1</tt>, the displacement field is not committed to the atoms
positions, but is stored/accumulated in array <tt>storedr</tt>, until this command is
(or other commands such as <tt>makedislocation</tt>) is called again with option 
<tt><i>store</i> = 0</tt>.

<p>
Note: atoms may need to be removed or inserted when executing this command.
If atoms need to be inserted, you will need to set <tt>allocmultiple</tt> to be
greater than 1 when calling <tt>makecrystal</tt> or <tt>readcn</tt> above.


<p>
Also see <tt>makedislocation</tt>.

<p>
Example: <tt>MD++/scripts/CSD-book/chap5/sect5.1/mo-screw-dipole.script</tt>

<p>
For details, see <a href="http://micro.stanford.edu/~caiwei/CSD-Book/">Computer Simulations
of Dislocations</a>, Chapter 5, Section 5.1.

