What closure relations can we use in molecular modelling?

Following my question [here](https://physics.stackexchange.com/questions/202500/the-liouville-equation-and-the-bbgky-hierarchy/202512?noredirect=1#comment433262_202512) about the BBGKY hierarchy I was wondering does anyone have any experience in *using* the method outlined. In particular how would I take an equation off the page and for some reduced phase space density or distribution function and start obtaining meaningful results and simulations? I understand that it is necessary to implement **closure relations** along the way. If anyone has experience in doing this sort of thing, could you outline (qualitatively) what steps I need to take etc. 


