Hello Justin, This is Anik again. I checked the links. But could not understand fully. Am giving the part of the topology file as given below, generated with the command
"pdb2gmx -f a.pdb -o b.pdb -p topol.top" The topology file : " 205 CL- 205 CL- Cl 205 -1 35.453 ; qtot 35 206 CL- 206 CL- Cl 206 -1 35.453 ; qtot 34 207 CL- 207 CL- Cl 207 -1 35.453 ; qtot 33 208 CL- 208 CL- Cl 208 -1 35.453 ; qtot 32 209 CL- 209 CL- Cl 209 -1 35.453 ; qtot 31 210 CL- 210 CL- Cl 210 -1 35.453 ; qtot 30 211 CL- 211 CL- Cl 211 -1 35.453 ; qtot 29 212 CL- 212 CL- Cl 212 -1 35.453 ; qtot 28 213 CL- 213 CL- Cl 213 -1 35.453 ; qtot 27 214 CL- 214 CL- Cl 214 -1 35.453 ; qtot 26 215 CL- 215 CL- Cl 215 -1 35.453 ; qtot 25 216 CL- 216 CL- Cl 216 -1 35.453 ; qtot 24 217 CL- 217 CL- Cl 217 -1 35.453 ; qtot 23 218 CL- 218 CL- Cl 218 -1 35.453 ; qtot 22 219 CL- 219 CL- Cl 219 -1 35.453 ; qtot 21 220 CL- 220 CL- Cl 220 -1 35.453 ; qtot 20 221 CL- 221 CL- Cl 221 -1 35.453 ; qtot 19 222 CL- 222 CL- Cl 222 -1 35.453 ; qtot 18 223 CL- 223 CL- Cl 223 -1 35.453 ; qtot 17 224 CL- 224 CL- Cl 224 -1 35.453 ; qtot 16 225 CL- 225 CL- Cl 225 -1 35.453 ; qtot 15 226 CL- 226 CL- Cl 226 -1 35.453 ; qtot 14 227 CL- 227 CL- Cl 227 -1 35.453 ; qtot 13 228 CL- 228 CL- Cl 228 -1 35.453 ; qtot 12 229 CL- 229 CL- Cl 229 -1 35.453 ; qtot 11 230 CL- 230 CL- Cl 230 -1 35.453 ; qtot 10 231 CL- 231 CL- Cl 231 -1 35.453 ; qtot 9 232 CL- 232 CL- Cl 232 -1 35.453 ; qtot 8 233 CL- 233 CL- Cl 233 -1 35.453 ; qtot 7 234 CL- 234 CL- Cl 234 -1 35.453 ; qtot 6 235 CL- 235 CL- Cl 235 -1 35.453 ; qtot 5 236 CL- 236 CL- Cl 236 -1 35.453 ; qtot 4 237 CL- 237 CL- Cl 237 -1 35.453 ; qtot 3 238 CL- 238 CL- Cl 238 -1 35.453 ; qtot 2 239 CL- 239 CL- Cl 239 -1 35.453 ; qtot 1 240 CL- 240 CL- Cl 240 -1 35.453 ; qtot 0 ; Include Position restraint file #ifdef POSRES #include "posre.itp" #endif ; Include water topology #include "tip4p.itp" #ifdef POSRES_WATER ; Position restraint for each water oxygen [ position_restraints ] ; i funct fcx fcy fcz 1 1 1000 1000 1000 #endif " This includes the posre.itp as follows: " ; In this topology include file, you will find position restraint ; entries for all the heavy atoms in your original pdb file. ; This means that all the protons which were added by pdb2gmx are ; not restrained. [ position_restraints ] ; atom type fx fy fz 215 1 1000 1000 1000 216 1 1000 1000 1000 217 1 1000 1000 1000 218 1 1000 1000 1000 219 1 1000 1000 1000 220 1 1000 1000 1000 221 1 1000 1000 1000 222 1 1000 1000 1000 223 1 1000 1000 1000 224 1 1000 1000 1000 225 1 1000 1000 1000 226 1 1000 1000 1000 227 1 1000 1000 1000 228 1 1000 1000 1000 229 1 1000 1000 1000 230 1 1000 1000 1000 231 1 1000 1000 1000 232 1 1000 1000 1000 233 1 1000 1000 1000 234 1 1000 1000 1000 235 1 1000 1000 1000 236 1 1000 1000 1000 237 1 1000 1000 1000 238 1 1000 1000 1000 239 1 1000 1000 1000 240 1 1000 1000 1000 " Now are these atoms already restrained, or we have to restrain tem by othr means.. As after the minimisation step, the atoms are moving from their positions, which i donot want. Please help in this matter. ________________________________________ From: gmx-users-boun...@gromacs.org [gmx-users-boun...@gromacs.org] on behalf of Anik Sen [anik...@csmcri.org] Sent: Tuesday, June 19, 2012 11:13 PM To: jalem...@vt.edu; Discussion list for GROMACS users Subject: RE: [gmx-users] to know about constraints Thanx Justin. I will check the links.. ________________________________________ From: gmx-users-boun...@gromacs.org [gmx-users-boun...@gromacs.org] on behalf of Justin A. Lemkul [jalem...@vt.edu] Sent: Tuesday, June 19, 2012 11:06 PM To: Discussion list for GROMACS users Subject: Re: [gmx-users] to know about constraints On 6/19/12 1:28 PM, Anik Sen wrote: > Dear gromacs developers, > > This is Anik. For a certain work with > nonbonded interactions with alkali halides and water, I need to constrain some > specific atoms in the energy minimization step. Is there any option to > constrain > the atoms in a specific calculation. The water molecules and other atoms may > be > in movement during the calculation. > I think what you're looking for are "restraints," not "constraints." Restraints inhibit motion; constraints fix bond lengths or angles. http://www.gromacs.org/Documentation/Terminology/Constraints_and_Restraints Position restraints are a common part of many workflows. These are likely what you need. http://www.gromacs.org/Documentation/How-tos/Position_Restraints -Justin -- ======================================== Justin A. Lemkul, Ph.D. Research Scientist 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. 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