Geometry Optimisation with CASTEP
Geometry Optimisation with CASTEP
Geometry Optimisation with CASTEP
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Next: Atomic masses Up: The .cell file and Previous: Constraints on the cell<br />
Constraints on the movement of ions<br />
(This page was written by D. Quigley and is taken from the Molecular<br />
Dynamics in <strong>CASTEP</strong> user guide).<br />
Any combination of linear constraints can be specified in the cell file.<br />
We assign the index to run over all species present in the cell, the index to run over the<br />
ions in each species, and the index to run over the three spatial co-ordinates of an ion. The coordinate<br />
of the 2nd ion in the 3rd species is then<br />
. Associated <strong>with</strong> each of these degrees<br />
of freedom is a co-efficient . The n linear constraint can then be specified as<br />
where the constant is determined by the initial conditions. Specification of the n linear constraint<br />
therefore reduces to specification of the co-efficients<br />
. These are input into the cell file in the<br />
following fashion.<br />
%BLOCK IONIC_CONSTRAINTS<br />
1 S j<br />
1 S j
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