I am considering the addition of periodic boundary conditions support to the BD simulation. I guess it would apply to any optimizer in IMP - what would be the technical complications? I guess naively,what is needed is mainly to reformulate the restraints in a periodic way, but I wonder if it affects any sort of score evaluator optimizations (ClosePairs, etc. - the latter is probably easy to handle  as it mainly affects particles at the boundary). In the future it will also allow periodically optimized restraints (such as ones using FFT).
Barak

p.s. in my particular case, I thought of PBC over the x,y plane only, if that matter for anything, which I believe it doesn't