OKK, But, before, I have tried using md as integrator where I start the initial velocity as 280K ( which makes sense as the minimized configuration is essentially at low temperature) and have used Nose-hoover at 300K and I never had problem in getting the desired 300K after running a short NVT simulation as equilabration. The problem arises when sd integrator is used. In fact, I just tried to generate the initial velocity at 300K along with sd integrator. I got the 303 K as average temperature again. The same simulation using md integrator always gives rise to 300K as average temperature( when used in conjunction with Nose-Hoover ) , even if I generate velocity at 280 K or 300K .
I guess that the initial velocity-generation temperature should not be an issue here. The sd integrator in contrast to md integrator may be the problem. ________________________________ From: Justin A. Lemkul <jalem...@vt.edu> To: Discussion list for GROMACS users <gmx-users@gromacs.org> Sent: Tue, August 2, 2011 8:40:21 PM Subject: Re: [gmx-users] Problem with temperature and stochastic dynamics in FEP Sanku M wrote: > Hi Justin, > So, do you suggest that after minimization, I should generate the velocity > at >300K instead ? > i.,e for equilibration,should following the set-up? > You should always equilibrate under the desired conditions. Never make sudden changes, or else you're going to damage the stability of the system. -Justin > gen-vel = yes >> > gen-temp = 300 >> > gen-seed = -1 > > ------------------------------------------------------------------------ > *From:* Justin A. Lemkul <jalem...@vt.edu> > *To:* Discussion list for GROMACS users <gmx-users@gromacs.org> > *Sent:* Tue, August 2, 2011 8:26:16 PM > *Subject:* Re: [gmx-users] Problem with temperature and stochastic dynamics > in >FEP > > > > Justin A. Lemkul wrote: > > > > > > Sanku M wrote: > >> Hi Justin, > >> I first performed two minimization using steep and l-bfgs as the method > on >the solvated system for each lambda. Then I ran a 500ps NVT simulation on >minimized system ( for each lambda) where essentially same .mdp file was used >except the following change: > >> gen-vel = yes > >> gen-temp = 280 > >> gen-seed = -1 > >> > >> So, essentially, I heated the minimized system up from 280 K with ref_t >300K using sd integrator. But, here also I found the average temperature goes >to >303 K( instead of 300 K) . > > > > Unless you did simulated annealing in between, you didn't heat the system, >you suddenly jolted the temperature, which is probably not stable. Maybe the >integrator/Langevin thermostat does not react well to these conditions. >Equilibrate under the conditions you wish to collect data. Your data >collection >uses NPT, so running NVT at a different temperature and suddenly changing the >temperature and introducing pressure coupling is not an appropriate procedure. >If nothing else, your data will be unreliable, even if your temperature was >correct. > > > > Sorry, misread the previous .mdp settings. You're still using NVT, but the >point about the temperature is still valid here. > > -Justin > > -- ======================================== > > Justin A. Lemkul > Ph.D. Candidate > ICTAS Doctoral Scholar > MILES-IGERT Trainee > Department of Biochemistry > Virginia Tech > Blacksburg, VA > jalemkul[at]vt.edu | (540) 231-9080 > http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin > > ======================================== > -- gmx-users mailing list gmx-users@gromacs.org ><mailto:gmx-users@gromacs.org> > http://lists.gromacs.org/mailman/listinfo/gmx-users > Please search the archive at >http://www.gromacs.org/Support/Mailing_Lists/Search before posting! > Please don't post (un)subscribe requests to the list. Use the www interface > or >send it to gmx-users-requ...@gromacs.org ><mailto:gmx-users-requ...@gromacs.org>. > Can't post? Read http://www.gromacs.org/Support/Mailing_Lists -- ======================================== Justin A. Lemkul Ph.D. Candidate ICTAS Doctoral Scholar MILES-IGERT Trainee Department of Biochemistry Virginia Tech Blacksburg, VA jalemkul[at]vt.edu | (540) 231-9080 http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin ======================================== -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. Can't post? Read http://www.gromacs.org/Support/Mailing_Lists Blacksburg, VA > jalemkul[at]vt.edu | (540) 231-9080 > http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin > > ======================================== > -- gmx-users mailing list gmx-users@gromacs.org ><mailto:gmx-users@gromacs.org> > http://lists.gromacs.org/mailman/listinfo/gmx-users > Please search the archive at >http://www.gromacs.org/Support/Mailing_Lists/Search before posting! > Please don't post (un)subscribe requests to the list. Use the www interface > or >send it to gmx-users-requ...@gromacs.org ><mailto:gmx-users-requ...@gromacs.org>. > Can't post? Read http://www.gromacs.org/Support/Mailing_Lists -- ======================================== Justin A. Lemkul Ph.D. Candidate ICTAS Doctoral Scholar MILES-IGERT Trainee Department of Biochemistry Virginia Tech Blacksburg, VA jalemkul[at]vt.edu | (540) 231-9080 http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin ======================================== -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. Can't post? Read http://www.gromacs.org/Support/Mailing_Lists Blacksburg, VA > jalemkul[at]vt.edu | (540) 231-9080 > http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin > > ======================================== > -- gmx-users mailing list gmx-users@gromacs.org ><mailto:gmx-users@gromacs.org> > http://lists.gromacs.org/mailman/listinfo/gmx-users > Please search the archive at >http://www.gromacs.org/Support/Mailing_Lists/Search before posting! > Please don't post (un)subscribe requests to the list. Use the www interface > or >send it to gmx-users-requ...@gromacs.org ><mailto:gmx-users-requ...@gromacs.org>. > Can't post? Read http://www.gromacs.org/Support/Mailing_Lists -- ======================================== Justin A. Lemkul Ph.D. Candidate ICTAS Doctoral Scholar MILES-IGERT Trainee Department of Biochemistry Virginia Tech Blacksburg, VA jalemkul[at]vt.edu | (540) 231-9080 http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin ======================================== -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. Can't post? Read http://www.gromacs.org/Support/Mailing_Lists Blacksburg, VA > jalemkul[at]vt.edu | (540) 231-9080 > http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin > > ======================================== > -- gmx-users mailing list gmx-users@gromacs.org ><mailto:gmx-users@gromacs.org> > http://lists.gromacs.org/mailman/listinfo/gmx-users > Please search the archive at >http://www.gromacs.org/Support/Mailing_Lists/Search before posting! > Please don't post (un)subscribe requests to the list. Use the www interface > or >send it to gmx-users-requ...@gromacs.org ><mailto:gmx-users-requ...@gromacs.org>. > Can't post? Read http://www.gromacs.org/Support/Mailing_Lists -- ======================================== Justin A. Lemkul Ph.D. Candidate ICTAS Doctoral Scholar MILES-IGERT Trainee Department of Biochemistry Virginia Tech Blacksburg, VA jalemkul[at]vt.edu | (540) 231-9080 http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin ======================================== -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
-- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. Can't post? Read http://www.gromacs.org/Support/Mailing_Lists