<DIV>hi, gmx group and all gmx usrs,</DIV>
<DIV>I am doing some MD simulations on CNT's (carbon nanotube) mechanical properties with GROMACS.</DIV>
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<DIV>first of all, thanks very much for all the suggestions before. I finally got a stable CNT structure with those helps. </DIV>
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<DIV>I am in trouble again. May anyone help me out:</DIV>
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<DIV>When I pull the tube, all the atoms flies everywhere at the second step. And, it's strange that at the beginning of the "mdrun", GMX said ,<BR>------------------------------------<BR>reading file ndx30.tpr, VERSION 3.3 (single precision)<BR>Reading parameter file pull10.ppa<BR>Groups: top<BR>Reference Group: bot<BR>Using 1 pull groups<BR>Using distance components 0 0 1<BR>starting mdrun 'ICE'<BR>20 steps, 0.0 ps.<BR> <BR>Warning: 1-4 interaction between 5 and 6 at distance 1.295 which is larger than<BR>the 1-4 table size 1.000 nm<BR>These are ignored for the rest of the simulation<BR>This usually means your system is exploding,<BR>if not, you should increase table-extension in your mdp file<BR>Writing final coordinates.<BR>-----------------------------------------------------</DIV>
<DIV>Which parameter in mdp or pull.ppa could lead to that? Is there probably anything wrong with my mdp file or maybe the gro file? How should I fix it?</DIV>
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<DIV>1. if I want to apply axial stretching (or compression) on the tube, I should use the AFM pulling code. Am I on the right way?</DIV>
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<DIV>2. should I do PR before running pulling? (I do not think it's necessary, but maybe it is the certain reason?)</DIV>
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<DIV>3. should I redo EM? but EM gave me the present gro with total potential very low.<BR>( Potential Energy = -5.5786455e+03<BR> Maximum force = 7.5916821e+02 on atom 267<BR> Norm of force = 5.8862563e+03 ) ----------- Is it ok?</DIV>
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<DIV>best wishes, and looking forward to any suggestions.</DIV>
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<DIV>Thanks a lot.</DIV>
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<DIV>Jacky Allon from SCUT<BR><A href="mailto:jackyxh@163.com">jackyxh@163.com</A></DIV>
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<DIV>Follows is the md.log file and pullout.ppa attached:<BR>----------------------------------md.log (below)<BR>Input Parameters:<BR> integrator = md<BR> nsteps = 20<BR> init_step = 0<BR> ns_type = Grid<BR> nstlist = 1<BR> ndelta = 2<BR> bDomDecomp = FALSE<BR> decomp_dir = 0<BR> nstcomm = 1<BR> comm_mode = Linear<BR> nstcheckpoint = 2<BR> nstlog = 1<BR> nstxout = 1<BR> nstvout = 100<BR> nstfout = 0<BR> nstenergy = 2<BR> nstxtcout = 0<BR> init_t = 0<BR> delta_t = 0.001<BR> xtcprec = 1000<BR> nkx = 0<BR> nky = 0<BR> nkz = 0<BR> pme_order = 4<BR> ewald_rtol = 1e-05<BR> ewald_geometry = 0<BR> epsilon_surface = 0<BR> optimize_fft = FALSE<BR> ePBC = full<BR> bUncStart = FALSE<BR> bShakeSOR = FALSE<BR> etc = Berendsen<BR> epc = No<BR> epctype = Isotropic<BR> tau_p = 1<BR> ref_p (3x3):<BR> ref_p[ 0]={ 0.00000e+00, 0.00000e+00, 0.00000e+00}<BR> ref_p[ 1]={ 0.00000e+00, 0.00000e+00, 0.00000e+00}<BR> ref_p[ 2]={ 0.00000e+00, 0.00000e+00, 0.00000e+00}<BR> compress (3x3):<BR> compress[ 0]={ 0.00000e+00, 0.00000e+00, 0.00000e+00}<BR> compress[ 1]={ 0.00000e+00, 0.00000e+00, 0.00000e+00}<BR> compress[ 2]={ 0.00000e+00, 0.00000e+00, 0.00000e+00}<BR> andersen_seed = 815131<BR> rlist = 0.24 ----------------------I have tried 1.0 and 1.2 too,but the result changed just a little<BR> coulombtype = Cut-off<BR> rcoulomb_switch = 0<BR> rcoulomb = 0.24 -----------------------And this too<BR> vdwtype = Cut-off<BR> rvdw_switch = 0<BR> rvdw = 0.24 ----------------------- And this.<BR> epsilon_r = 1<BR> epsilon_rf = 1<BR> tabext = 1<BR> gb_algorithm = Still<BR> nstgbradii = 1<BR> rgbradii = 2<BR> gb_saltconc = 0<BR> implicit_solvent = No<BR> DispCorr = No<BR> fudgeQQ = 1<BR> free_energy = no<BR> init_lambda = 0<BR> sc_alpha = 0<BR> sc_power = 1<BR> sc_sigma = 0.3<BR> delta_lambda = 0<BR> disre_weighting = Conservative<BR> disre_mixed = FALSE<BR> dr_fc = 1000<BR> dr_tau = 0<BR> nstdisreout = 100<BR> orires_fc = 0<BR> orires_tau = 0<BR> nstorireout = 100<BR> dihre-fc = 1000<BR> dihre-tau = 0<BR> nstdihreout = 100<BR> em_stepsize = 0.01<BR> em_tol = 10<BR> niter = 20<BR> fc_stepsize = 0<BR> nstcgsteep = 1000<BR> nbfgscorr = 10<BR> ConstAlg = Lincs<BR> shake_tol = 1e-04<BR> lincs_order = 4<BR> lincs_warnangle = 30<BR> lincs_iter = 1<BR> bd_fric = 0<BR> ld_seed = 1993<BR> cos_accel = 0<BR> deform (3x3):<BR> deform[ 0]={ 0.00000e+00, 0.00000e+00, 0.00000e+00}<BR> deform[ 1]={ 0.00000e+00, 0.00000e+00, 0.00000e+00}<BR> deform[ 2]={ 0.00000e+00, 0.00000e+00, 0.00000e+00}<BR> userint1 = 0<BR> userint2 = 0<BR> userint3 = 0<BR> userint4 = 0<BR> userreal1 = 0<BR> userreal2 = 0<BR> userreal3 = 0<BR> userreal4 = 0<BR>grpopts:<BR> nrdf: 2067<BR> ref_t: 300<BR> tau_t: 0.1<BR>anneal: No<BR>ann_npoints: 0<BR> acc: 0 0 0<BR> nfreeze: Y Y Y N N N<BR> energygrp_flags[ 0]: 0<BR> efield-x:<BR> n = 0<BR> efield-xt:<BR> n = 0<BR> efield-y:<BR> n = 0<BR> efield-yt:<BR> n = 0<BR> efield-z:<BR> n = 0<BR> efield-zt:<BR> n = 0<BR> bQMMM = FALSE<BR> QMconstraints = 0<BR> QMMMscheme = 0<BR> scalefactor = 1<BR>qm_opts:<BR> ngQM = 0<BR>CPU= 0, lastcg= 699, targetcg= 350, myshift= 0<BR>nsb->shift = 1, nsb->bshift= 0<BR>Neighbor Search Blocks<BR>nsb->nodeid: 0<BR>nsb->nnodes: 1<BR>nsb->cgtotal: 700<BR>nsb->natoms: 700<BR>nsb->shift: 1<BR>nsb->bshift: 0<BR>Nodeid index homenr cgload workload<BR> 0 0 700 700 700</DIV>
<DIV>Table routines are used for coulomb: FALSE<BR>Table routines are used for vdw: FALSE<BR>Cut-off's: NS: 0.24 Coulomb: 0.24 LJ: 0.24<BR>System total charge: 0.000<BR>Generated table with 500 data points for 1-4 COUL.<BR>Tabscale = 500 points/nm<BR>Generated table with 500 data points for 1-4 LJ6.<BR>Tabscale = 500 points/nm<BR>Generated table with 500 data points for 1-4 LJ12.<BR>Tabscale = 500 points/nm<BR>Center of mass motion removal mode is Linear<BR>We have the following groups for center of mass motion removal:<BR> 0: rest, initial mass: 8400<BR>There are: 700 Atoms<BR>Removing pbc first time<BR>Done rmpbc</DIV>
<DIV>**************************************************<BR> PULL INFO <BR>**************************************************<BR>RUN TYPE: Afm<BR>REFERENCE TYPE: center of mass of reference group<BR>Looking for group top: found group top: 10 elements. First: 658 </DIV>
<DIV> ---pulled group, one side of the tube<BR>Looking for group bot: found group bot: 10 elements. First: 1 </DIV>
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<DIV> ----ref group, the other side of the tube</DIV>
<DIV><BR>Initializing pull groups. Inv. mass of group 1: 0.008333<BR>Initial coordinates center of mass: 1.500 1.500 14.243</DIV>
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<DIV> ----box 3 3 20 and length of tube 8.488</DIV>
<DIV><BR>Initializing reference group. Inv. mass: 0.000000<BR>Initial coordinates center of mass: 0.000 0.000 0.000<BR>Initial distance of group 1: 5.757</DIV>
<DIV>Pull rate: 1.000000e-03 nm/ns. Force constant: 1.680000e+03 kJ/(mol nm)<BR>Pull direction: 0.000 -0.000 -1.000 </DIV>
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<DIV> ------Strange? But I set "afm_dir1 = 0.0 0.0 1.0"</DIV>
<DIV><BR>Started mdrun on node 0 Sun Jul 30 03:30:54 2006<BR>Initial temperature: 304.385 K<BR> Step Time Lambda<BR> 0 0.00000 0.00000</DIV>
<DIV>Grid: 25 x 25 x 166 cells<BR>Configuring nonbonded kernels...<BR>Testing AMD 3DNow support... not present.<BR>Testing ia32 SSE support... present.</DIV>
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<DIV>++++ PLEASE READ AND CITE THE FOLLOWING REFERENCE ++++<BR>H. J. C. Berendsen, J. P. M. Postma, A. DiNola and J. R. Haak<BR>Molecular dynamics with coupling to an external bath<BR>J. Chem. Phys. 81 (1984) pp. 3684-3690<BR>-------- -------- --- Thank You --- -------- --------</DIV>
<DIV>Large VCM(group rest): 0.04424, 0.00987, 0.01367, ekin-cm: 9.41453e+00<BR> Energies (kJ/mol)<BR> Morse Angle Proper Dih. LJ-14 Coulomb-14<BR> 1.23930e+05 2.50185e+02 2.24203e+03 -8.04751e+03 0.00000e+00<BR> LJ (SR) Coulomb (SR) Potential Kinetic En. Total Energy<BR> 0.00000e+00 0.00000e+00 1.18375e+05 4.63024e+06 4.74861e+06<BR> Temperature Pressure (bar)<BR> 5.38835e+05 1.13207e+06</DIV>
<DIV> Step Time Lambda<BR> 1 0.00100 0.00000</DIV>
<DIV>Large VCM(group rest): -0.03441, 0.03032, 11.52306, ekin-cm: 5.57689e+05<BR> Energies (kJ/mol)<BR> Morse Angle Proper Dih. LJ-14 Coulomb-14<BR> 1.62589e+08 1.52028e+05 2.77182e+03 1.35415e+05 0.00000e+00<BR> LJ (SR) Coulomb (SR) Potential Kinetic En. Total Energy<BR> 0.00000e+00 0.00000e+00 1.62880e+08 5.84601e+09 6.00889e+09<BR> Temperature Pressure (bar)<BR> 6.80318e+08 3.82511e+08</DIV>
<DIV> Step Time Lambda<BR> 2 0.00200 0.00000</DIV>
<DIV>Large VCM(group rest): -0.00575, 0.01008, 0.12466, ekin-cm: 6.58298e+01<BR> Energies (kJ/mol)<BR> Morse Angle Proper Dih. LJ-14 Coulomb-14<BR> 4.93545e+08 1.10614e+06 1.26717e+04 8.64429e+03 0.00000e+00<BR> LJ (SR) Coulomb (SR) Potential Kinetic En. Total Energy<BR> 7.72732e+09 0.00000e+00 8.22199e+09 1.38166e+17 1.38166e+17<BR> Temperature Pressure (bar)<BR> 1.60788e+16 8.49739e+15</DIV>
<DIV> Step Time Lambda<BR> 3 0.00300 0.00000</DIV>
<DIV>Large VCM(group rest): -25.96824, 170.04892, 230.66357, ekin-cm: 3.47746e+08<BR> Energies (kJ/mol)<BR> Morse Angle Proper Dih. LJ-14 Coulomb-14<BR> 4.95650e+08 7.87158e+05 1.35144e+04 -4.57799e+01 0.00000e+00<BR> LJ (SR) Coulomb (SR) Potential Kinetic En. Total Energy<BR> 3.75407e+14 0.00000e+00 3.75408e+14 8.77067e+26 8.77067e+26<BR> Temperature Pressure (bar)<BR> 1.02067e+26 5.39409e+25</DIV>
<DIV> Step Time Lambda<BR> 4 0.00400 0.00000</DIV>
<DIV> Energies (kJ/mol)<BR> Morse Angle Proper Dih. LJ-14 Coulomb-14<BR> 4.95603e+08 7.18547e+05 1.31598e+04 4.71733e+01 0.00000e+00<BR> LJ (SR) Coulomb (SR) Potential Kinetic En. Total Energy<BR> 1.48841e+11 0.00000e+00 1.49337e+11 nan nan<BR> Temperature Pressure (bar)<BR> nan nan</DIV>
<DIV> Step Time Lambda<BR> 5 0.00500 0.00000</DIV>
<DIV>-------------------------------------------------------<BR>Program mdrun, VERSION 3.3<BR>Source code file: nsgrid.c, line: 226</DIV>
<DIV>Range checking error:<BR>Explanation: During neighborsearching, we assign each particle to a grid<BR>based on its coordinates. If your system contains collisions or parameter<BR>errors that give particles very high velocities you might end up with some<BR>coordinates being +-Infinity or NaN (not-a-number). Obviously, we cannot<BR>put these on a grid, so this is usually where we detect those errors.<BR>Make sure your system is properly energy-minimized and that the potential<BR>energy seems reasonable before trying again.</DIV>
<DIV>Variable ci has value -2147483648. It should have been within [ 0 .. 103750 ]<BR>Please report this to the mailing list (<A href="mailto:gmx-users@gromacs.org">gmx-users@gromacs.org</A>)<BR>-------------------------------------------------------</DIV>
<DIV>"Don't Grumble, Give a Whistle !" (Monty Python)<BR>----------------------------------------md.log (above)</DIV>
<DIV>==========================pullout.ppa (below)<BR>;<BR>; File 'pullout.ppa' was generated<BR>; By user: root (0)<BR>; On host: localhost.localdomain<BR>; At date: Sat Jul 22 20:43:49 2006<BR>;<BR>; GENERAL <BR>verbose = no<BR>Skip steps = 1<BR>; Runtype: afm, constraint, umbrella<BR>runtype = afm<BR>; Number of pull groups <BR>ngroups = 1<BR>; Groups to be pulled <BR>group_1 = top<BR>; The group for the reaction force.<BR>reference_group = bot<BR>; Weights for all atoms in each group (default all 1)<BR>weights_1 = <BR>reference_weights = <BR>; Ref. type: com, com_t0, dynamic, dynamic_t0<BR>reftype = com<BR>; Use running average for reflag steps for com calculation<BR>reflag = 1<BR>; Select components for the pull vector. default: Y Y Y<BR>pulldim = N N Y<BR>; DYNAMIC REFERENCE GROUP OPTIONS<BR>; Cylinder radius for dynamic reaction force groups (nm)<BR>r = 0<BR>; Switch from r to rc in case of dynamic reaction force<BR>rc = 0<BR>; Update frequency for dynamic reference groups (steps)<BR>update = 1</DIV>
<DIV>; CONSTRAINT RUN OPTIONS<BR>; Direction, default: 0 0 0, no direction<BR>constraint_direction = 0.0 0.0 0.0<BR>; Constraint distance (nm), default: 0, use starting distance<BR>constraint_distance1 = 0<BR>; Rate of chance of the constraint length, in nm/ps<BR>constraint_rate1 = 0<BR>; Tolerance of constraints, in nm<BR>constraint_tolerance = 1e-06</DIV>
<DIV>; AFM OPTIONS <BR>; Pull rates in nm/ps <BR>afm_rate1 = 0.001<BR>; Force constants in kJ/(mol*nm^2)<BR>afm_k1 = 1680<BR>; Directions <BR>afm_dir1 = 0.0 0.0 1.0<BR>; Initial spring positions<BR>afm_init1 = 0 0 8.488</DIV>
<DIV>; UMBRELLA SAMPLING OPTIONS<BR>; Force constants for umbrella sampling in kJ/(mol*nm^2)<BR>; Centers of umbrella potentials with respect to reference:<BR>; Ref - Pull. <BR>K1 = 0<BR>Pos1 = 0.0 0.0 0.0<BR>=================================pullout.ppa (above)<BR></DIV>
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<DIV> </DIV><SPAN >--<BR>If you send me one, I will always Re you three, friendship, help or anything else except emails and money:) ——Jacky Allon</SPAN><br><!-- footer --><br><br><br><br><br><div style="border-bottom:1px solid #999"></div><br>
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