[gmx-users] Lipids forming unsual bonds
"the lipids are forming usual cross bonds (seen in the form of long straight lines)" lines? on what? You need to do a much better job of describing your problem and your observations before anyone can give you a better suggestion than "remove those lines and everything will be solved"... That said, you're probably running into a regular pbc issue in vmd and you should then start with a .gro developed from trjconv -pbc mol or else you might try the "dynamic bonds" vmd representation. Otherwise, perhaps you are talking about loading in a post-equilibration .gro wherein the bond determination routine is finding "bonds" that don't make any sense and therefore your parameters or EM are probably bad. Still, a better description gets better assistance. Chris. -- original message -- Hi ALL, I am simulating a GPCR protein in a POPC bilayer. I have followed Justins' tutorial to set up the system, but have used POPC instead of DPPC. I have used the same parameters given in that tutorial. Till equilibration everything went well. But after releasing the protein in the production MD, the lipids are forming usual cross bonds (seen in the form of long straight lines). How can I avoid this? Any suggestion is welcome. Parameters used for MD: -- title= GPCR in POPC Production MD ; Run parameters integrator= md; leap-frog integrator nsteps= 50; 2 * 50 = 1000 ps (1 ns) dt= 0.002; 2 fs ; Output control nstxout= 1000; save coordinates every 2 ps nstvout= 1000; save velocities every 2 ps nstxtcout= 1000; xtc compressed trajectory output every 2 ps nstenergy= 1000; save energies every 2 ps nstlog= 1000; update log file every 2 ps ; Bond parameters continuation= yes; Restarting after NPT constraint_algorithm = lincs; holonomic constraints constraints= all-bonds; all bonds (even heavy atom-H bonds) constrained lincs_iter= 1; accuracy of LINCS lincs_order= 4; also related to accuracy ; Neighborsearching ns_type= grid; search neighboring grid cels nstlist= 5; 10 fs rlist= 1.2; short-range neighborlist cutoff (in nm) rcoulomb= 1.2; short-range electrostatic cutoff (in nm) rvdw= 1.2; short-range van der Waals cutoff (in nm) ; Electrostatics coulombtype= PME; Particle Mesh Ewald for long-range electrostatics pme_order= 4; cubic interpolation fourierspacing= 0.16; grid spacing for FFT ; Temperature coupling is on tcoupl= Nose-Hoover; More accurate thermostat tc-grps= Protein POPCSOL_CL-; three coupling groups - more accurate tau_t= 0.10.10.1; time constant, in ps ref_t= 323 323323; reference temperature, one for each group, in K ; Pressure coupling is on pcoupl= Parrinello-Rahman; Pressure coupling on in NPT pcoupltype= semiisotropic; uniform scaling of x-y box vectors, independent z tau_p= 2.0; time constant, in ps ref_p= 1.01.0; reference pressure, x-y, z (in bar) compressibility = 4.5e-54.5e-5; isothermal compressibility, bar^-1 ; Periodic boundary conditions pbc= xyz; 3-D PBC ; Dispersion correction DispCorr= EnerPres; account for cut-off vdW scheme ; Velocity generation gen_vel= no; Velocity generation is off --- Regards, Anirban GhoshGrade Based Engineer Bioinformatics Team Centre for Development of Advanced Computing (C-DAC) Pune, India Explore and discover exciting holidays and getaways with Yahoo! India Travel http://in.travel.yahoo.com/ -- next part -- An HTML attachment was scrubbed... URL: http://www.gromacs.org/pipermail/gmx-users/attachments/20090521/320022c5/attachment.html -- ___ gmx-users mailing listgmx-users@gromacs.org http://www.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/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/mailing_lists/users.php
Re: [gmx-users] Lipids forming unsual bonds
Anirban Ghosh wrote: Hi ALL, I am simulating a GPCR protein in a POPC bilayer. I have followed Justins' tutorial to set up the system, but have used POPC instead of DPPC. I have used the same parameters given in that tutorial. Till equilibration everything went well. But after releasing the protein in the production MD, the lipids are forming usual cross bonds (seen in the form of long straight lines). How can I avoid this? Any suggestion is welcome. Bonds don't form in MD. Probably, the heuristic that your visualization software is using to guess where bonds exist isn't working the way you expected. I can't tell from your description, but you may being seeing "bonds" across the simulation box when the periodic boundaries intersect with molecules. Mark ___ gmx-users mailing listgmx-users@gromacs.org http://www.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/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/mailing_lists/users.php
RE: [gmx-users] Lipids forming unsual bonds
What exactly do you mean by "unusual cross bonds"? I suspect what you are seeing is simply a visualisation artifact, with a molecule being displayed across a PBC in the viewer you are using. Catch ya, Dr. Dallas Warren Department of Pharmaceutical Biology and Pharmacology Pharmacy and Pharmaceutical Sciences, Monash University 381 Royal Parade, Parkville VIC 3010 dallas.war...@pharm.monash.edu.au +61 3 9903 9167 - When the only tool you own is a hammer, every problem begins to resemble a nail. ___ gmx-users mailing listgmx-users@gromacs.org http://www.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/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/mailing_lists/users.php
[gmx-users] Lipids forming unsual bonds
Hi ALL, I am simulating a GPCR protein in a POPC bilayer. I have followed Justins' tutorial to set up the system, but have used POPC instead of DPPC. I have used the same parameters given in that tutorial. Till equilibration everything went well. But after releasing the protein in the production MD, the lipids are forming usual cross bonds (seen in the form of long straight lines). How can I avoid this? Any suggestion is welcome. Parameters used for MD: -- title = GPCR in POPC Production MD ; Run parameters integrator = md ; leap-frog integrator nsteps = 50 ; 2 * 50 = 1000 ps (1 ns) dt = 0.002 ; 2 fs ; Output control nstxout = 1000 ; save coordinates every 2 ps nstvout = 1000 ; save velocities every 2 ps nstxtcout = 1000 ; xtc compressed trajectory output every 2 ps nstenergy = 1000 ; save energies every 2 ps nstlog = 1000 ; update log file every 2 ps ; Bond parameters continuation = yes ; Restarting after NPT constraint_algorithm = lincs ; holonomic constraints constraints = all-bonds ; all bonds (even heavy atom-H bonds) constrained lincs_iter = 1 ; accuracy of LINCS lincs_order = 4 ; also related to accuracy ; Neighborsearching ns_type = grid ; search neighboring grid cels nstlist = 5 ; 10 fs rlist = 1.2 ; short-range neighborlist cutoff (in nm) rcoulomb = 1.2 ; short-range electrostatic cutoff (in nm) rvdw = 1.2 ; short-range van der Waals cutoff (in nm) ; Electrostatics coulombtype = PME ; Particle Mesh Ewald for long-range electrostatics pme_order = 4 ; cubic interpolation fourierspacing = 0.16 ; grid spacing for FFT ; Temperature coupling is on tcoupl = Nose-Hoover ; More accurate thermostat tc-grps = Protein POPC SOL_CL- ; three coupling groups - more accurate tau_t = 0.1 0.1 0.1 ; time constant, in ps ref_t = 323 323 323 ; reference temperature, one for each group, in K ; Pressure coupling is on pcoupl = Parrinello-Rahman ; Pressure coupling on in NPT pcoupltype = semiisotropic ; uniform scaling of x-y box vectors, independent z tau_p = 2.0 ; time constant, in ps ref_p = 1.0 1.0 ; reference pressure, x-y, z (in bar) compressibility = 4.5e-5 4.5e-5 ; isothermal compressibility, bar^-1 ; Periodic boundary conditions pbc = xyz ; 3-D PBC ; Dispersion correction DispCorr = EnerPres ; account for cut-off vdW scheme ; Velocity generation gen_vel = no ; Velocity generation is off --- Regards, Anirban GhoshGrade Based Engineer Bioinformatics Team Centre for Development of Advanced Computing (C-DAC) Pune, India Explore and discover exciting holidays and getaways with Yahoo! India Travel http://in.travel.yahoo.com/___ gmx-users mailing listgmx-users@gromacs.org http://www.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/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/mailing_lists/users.php
