Sir, I did a 10 ns REMD simulation for a peptide, 8 replicas using amber force field.Then extracted pdb file from the trajectory and clustered using g_cluster. The I viewed the average structure of the cluster in pymol .But here the atoms are merged togather.why it happends?Is there any problem with my force field? My md.mdp file as follows.
RESHELIX ; -DFLEXIBLE -DPOSRES constraints = none integrator = md dt = 0.001 ; ps nsteps = 10000000 ; 10000 ps = 10 ns nstcomm = 10 nstcalcenergy = 10 nstxout = 500 ; frequency to write coordinates to output trajectory nstvout = 0 ; frequency to write velocities to output trajectory; the last velocities are always written nstfout = 0 ; frequency to write forces to output trajectory nstlog = 1000 ; frequency to write energies to log file nstenergy = 1000 ; frequency to write energies to edr file vdwtype = cut-off coulombtype = cut-off pbc = no nstlist = 0 ns_type = simple rlist = 0 ; this means all-vs-all (no cut-off), which gets expensive for bigger systems rcoulomb = 0 rvdw = 0 comm-mode = angular comm-grps = system optimize_fft = yes ; V-rescale temperature coupling is on Tcoupl = v-rescale tau_t = 0.1 tc_grps = system ref_t = 376.32 ; Pressure coupling is off Pcoupl = no ; Generate velocites is on gen_vel = yes gen_temp = 270 gen_seed = -1 ; ; Implicit solvent ; implicit_solvent = GBSA gb_algorithm = Still ; HCT ; OBC nstgbradii = 1 rgbradii = 0 ; [nm] Cut-off for the calculation of the Born radii. Currently must be equal to rlist gb_epsilon_solvent = 80 ; Dielectric constant for the implicit solvent ; gb_saltconc = 0 ; Salt concentration for implicit solvent models, currently not used sa_algorithm = Ace-approximation sa_surface_tension = -1 -- 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