On 6/1/17 4:28 PM, Alex wrote:
Just a few quick questions for Justin. I am looking at your tutorial, starting here: http://bevanlab.biochem.vt.edu/Pages/Personal/justin/gmx-tutorials/umbrella/05_pull.html 1. In your example, you have two pull groups. My understanding is that both are pulled relative to each other. In my case, the only thing that's pulled to create the series of configurations required for WHAM is a single ion, which is pulled relative to the rest of the system (nothing but a hydrated membrane with a particular type of hole inside of it). The ion starts above the hole, enters the hole, then leaves it, the aim here is to find the free energy associated with sitting in that hole. I recall (maybe incorrectly) that pull code has some quirks, so will your procedure work, or is there anything I should be aware of?
Your situation is completely different. Look into the cylinder settings for dealing with a layered system, but I have no experience with them. To be clear - you always need two groups to define the vector (reaction coordinate) along which the bias is applied. So you need to define a second group; you can't just say "I'm biasing an ion and that's it."
2. It is my understanding that only pullx and pullf files are required for WHAM, along with the tpr's for each of the MD runs, at least that's what follows from the tutorial. Anything about trajectories or energy files? May I just clean those up in my script, or will they be needed at any point?
Might be useful for troubleshooting or inspecting the microscopic behavior that gives rise to the free energy profile. There's always useful stuff there; rarely do you only care about just a single number coming out of WHAM.
-Justin -- ================================================== Justin A. Lemkul, Ph.D. Ruth L. Kirschstein NRSA Postdoctoral Fellow Department of Pharmaceutical Sciences School of Pharmacy Health Sciences Facility II, Room 629 University of Maryland, Baltimore 20 Penn St. Baltimore, MD 21201 jalem...@outerbanks.umaryland.edu | (410) 706-7441 http://mackerell.umaryland.edu/~jalemkul ================================================== -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.