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Unformatted text preview: I Obviously, no real system is exactly of this shape. Further, it is impossible to model (most of the) real system sizes. I Hence, we need to carefully consider how our simulation model can be made to represent a larger system. Periodic Boundary Conditions (pbc) I For example, if we are interested in bulk properties, we can introduce periodic boundary conditions to estimate the behaviour of an infinite system. I This approach involves “copying” the simulation cell to each of the periodic directions (1–3) so that our initial system “sees” another system, exactly like itself, in each direction around it. So, we’ve created a virtual crystal. I Now, if an atom moves out, if comes back in from the other side. Notes Example: pbc for a 2D system I Note that the nearest neighbors of atom A, except for B, are now in the neighbouring “virtual” cells instead of the original cell. I Obviously, this has to be taken into account when evaluating the potential U ( r ) ....
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This note was uploaded on 02/14/2012 for the course CSE 6590 taught by Professor Kotakoski during the Winter '12 term at York University.
- Winter '12