Dear users, I am trying to simulate a non protein molecule and have included the necessary parameters in the ff*.rtp file. I first encountered an error in the grompp step, so i modified my .mdp files such that the rlist, rvdw and rcoulomb values are set to 0.5. Now, while carrying out the mdrun for the position restraint step, I am getting a segmentation fault and a LINCS warning for the dihedrals that exceed 30. I do not know how to proceed and I'm using version 3.3.3 so the bug in the earlier version should have been fixed. I have also tried other suggestions in the forum with no effect. Here is my pr.mdp file
title = cpeptide position restraining warnings = 10 cpp = /lib/cpp define = -DPOSRES constraints = all-bonds integrator = md dt = 0.002 ; ps ! nsteps = 10000 ; total 20.0 ps. nstcomm = 1 nstxout = 10 nstvout = 1000 nstfout = 0 nstlog = 10 nstenergy = 10 nstlist = 10 ns_type = grid fourierspacing = 0.12 pme_order = 4 ewald_rtol = 1e-5 rlist = 0.5 coulombtype = PME rcoulomb = 0.5 rvdw = 0.5 ; Berendsen temperature coupling is on in two groups Tcoupl = berendsen tau_t = 0.1 0.1 tc-grps = Protein other ref_t = 300 300 ; Pressure coupling is not on Pcoupl = no tau_p = 0.5 compressibility = 4.5e-5 ref_p = 1.0 ; Generate velocites is on at 300 K. gen_vel = yes gen_temp = 300.0 gen_seed = 173529 and this is the error I am encountering. Back Off! I just backed up md.log to ./#md.log.2# Reading file NOR_pr.tpr, VERSION 3.3.3 (single precision) Back Off! I just backed up ener.edr to ./#ener.edr.2# starting mdrun 'Protein in water' 10000 steps, 20.0 ps. Step 0, time 0 (ps) LINCS WARNING relative constraint deviation after LINCS: max 361281.968750 (between atoms 2 and 7) rms 231973.328125 bonds that rotated more than 30 degrees: atom 1 atom 2 angle previous, current, constraint length 1 2 89.7 0.1530 43840.2148 0.1530 1 5 89.8 0.1530 44279.3516 0.1530 2 3 89.3 0.1530 51527.6133 0.1530 2 7 89.1 0.1530 55276.2969 0.1530 3 4 89.5 0.1530 22948.2949 0.1530 3 6 88.5 0.1530 20192.1895 0.1530 4 5 88.8 0.1530 8407.1387 0.1530 4 7 89.3 0.1530 26344.8340 0.1530 5 6 91.3 0.1530 33359.8477 0.1530 6 7 88.6 0.1530 13846.0684 0.1530 Segmentation fault I have been trying to solve this problem for quite some time now. It would be very helpful if you can suggest some way to work around this problem. regards Rukmani Sridharan
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