[MMTK] Trying to write a Monte Carlo code -- problems with coordinate changes

[khinsen@cea.fr]

Georg Ganzenmueller writes: 

> The code (please see below) runs initially O.K. but after a few 
> iterations in isweep, the energy rises to very high numbers. Inspection 
> of the final configuration of the molecules with rasmol shows molecules 
> torn apart (that is, hydrogens at one place, oygens at some other 
> place). This does not happen, if I use ONLY rotation or ONLY translation 
> attempts.

I suspect that the cause of your problem is periodic boundary conditions. If 
a molecule is close to the edge of the box, an atom can easily move across 
to the other side and thus appear remote, though the minimum-image distance 
remains small. 

Konrad