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Option: dislocation

Syntax

-dislocation <disloctype> <dislocline> <b> <poisson> <pos1> <pos2>

or

-disloc <disloctype> <dislocline> <b> <poisson> <pos1> <pos2>

Description

This option allows to insert a straight edge or screw dislocation in the system.

The user has to provide the following parameters:

In the case of an edge dislocation, new atoms are inserted in the system and then atomic displacements are applied. So beware that this option changes the total number of atoms in the system. Due to these displacements, the supercell vectors are also a bit elongated in the direction of the Burgers vector -it is recommended that you check them afterwards.

Inserting a screw dislocation conserves the number of atoms as well as the cell vectors.

Note that b can take negative values. This can be useful for instance if you want to insert dislocations of opposite Burgers vectors in the same supercell.

Beware that pikashu does not "automagically" find the Burgers vector, so you have to provide a very precise value of b. Neither does the program find the "best" position for the dislocation center: if you specify a position pos1, pos2 that exactly matches an atom position you may end up with unrealistic displacements, so you may have to play around with the dislocation coordinates to obtain proper results. As usual, don't trust a program blindly -check your system before running any simulation, specially when building systems with dislocation(s).

Default is <b> = 0 (i.e. no dislocation is introduced at all).

Examples

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