{"action":"created","issue":{"url":"https://api.github.com/repos/pandegroup/openmm/issues/886","labels_url":"https://api.github.com/repos/pandegroup/openmm/issues/886/labels{/name}","comments_url":"https://api.github.com/repos/pandegroup/openmm/issues/886/comments","events_url":"https://api.github.com/repos/pandegroup/openmm/issues/886/events","html_url":"https://github.com/pandegroup/openmm/issues/886","id":72269851,"number":886,"title":"[FR] Solvate with fixed number of waters","user":{"login":"cxhernandez","id":5142365,"avatar_url":"https://avatars.githubusercontent.com/u/5142365?v=3","gravatar_id":"","url":"https://api.github.com/users/cxhernandez","html_url":"https://github.com/cxhernandez","followers_url":"https://api.github.com/users/cxhernandez/followers","following_url":"https://api.github.com/users/cxhernandez/following{/other_user}","gists_url":"https://api.github.com/users/cxhernandez/gists{/gist_id}","starred_url":"https://api.github.com/users/cxhernandez/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/cxhernandez/subscriptions","organizations_url":"https://api.github.com/users/cxhernandez/orgs","repos_url":"https://api.github.com/users/cxhernandez/repos","events_url":"https://api.github.com/users/cxhernandez/events{/privacy}","received_events_url":"https://api.github.com/users/cxhernandez/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":21,"created_at":"2015-04-30T20:16:34Z","updated_at":"2015-05-01T17:52:21Z","closed_at":null,"body":"I think one thing that's been a big headache for people who are trying to make reproducible clones of simulations has been getting a fixed number of solvent molecules. I think It would be nice to add this functionality into `Modeller`. \r\n\r\nI have a prototype of the code on this [gist](https://gist.github.com/cxhernandez/5afae8cce3dcb034ee95), which is based off of @choderalab's [Ensembler](https://github.com/choderalab/ensembler/blob/aa3cfe690017ad0bb3dce49158ce8e6f31fb0127/ensembler/refinement.py#L565-L683) code."},"comment":{"url":"https://api.github.com/repos/pandegroup/openmm/issues/comments/98187224","html_url":"https://github.com/pandegroup/openmm/issues/886#issuecomment-98187224","issue_url":"https://api.github.com/repos/pandegroup/openmm/issues/886","id":98187224,"user":{"login":"jchodera","id":3656088,"avatar_url":"https://avatars.githubusercontent.com/u/3656088?v=3","gravatar_id":"","url":"https://api.github.com/users/jchodera","html_url":"https://github.com/jchodera","followers_url":"https://api.github.com/users/jchodera/followers","following_url":"https://api.github.com/users/jchodera/following{/other_user}","gists_url":"https://api.github.com/users/jchodera/gists{/gist_id}","starred_url":"https://api.github.com/users/jchodera/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jchodera/subscriptions","organizations_url":"https://api.github.com/users/jchodera/orgs","repos_url":"https://api.github.com/users/jchodera/repos","events_url":"https://api.github.com/users/jchodera/events{/privacy}","received_events_url":"https://api.github.com/users/jchodera/received_events","type":"User","site_admin":false},"created_at":"2015-05-01T17:52:21Z","updated_at":"2015-05-01T17:52:21Z","body":">  Why do you want the box to contain precisely N molecules? Are there cases where you want to specify a maximum number of molecules (as in #518)? Is it important for the box size to be fixed? Is it important for the results to be deterministic?\r\n\r\nOne of many reasons: Reweighting techniques (e.g. MBAR) require you have a potential energy function U(x;lambda) where you can feed it different configurations `x_n, n=1..N` that all have the same dimension.  Work on transdimensional reweighting is ongoing, but we don't have the theory for that yet.  Even if we did, it would almost certainly be much more complex."}}