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<div>Hi</div>
<div>Sorry that i have posted the same message for several times.</div>
<div><br>I used Gromacs version 3.3.3.<br>My simulation system = one protein + 20 ligand + water molecules ( 7x 7x 7<br>)<br>MPI setting =&gt; #PBS -l nodes=4:ppn=4,arch=x86_64   =&gt; 16 nodes in total<br>After doing the energy minimization, =&gt; the potential energy is extremely<br>
high ( say, ten to the 9th order )<br>I visualized the &quot; Simulation-System-EM-solvated.gro &quot; after the energy<br>minimization.<br>Then, I found that the Simulation Sysmtem is devided into 16 domains very<br>clearly and the molecules (protein, ligand, and water) break into atoms in<br>
the boundaries.<br>I have checked that the 20 ligands are not overlapped each other and are not<br>overlapped with protein from the beginning.<br> <br>More, i have created 10 alike system and each is with &quot;one protein + 20<br>
ligand + water molecules&quot;<br>Two of them get the &quot;minus potential energy&quot; after energy minimization and I<br>can continue running the MD simulation successfully.<br>Others of them get the &quot;extreme high positive potential energy&quot; and the<br>
system is devided into 16 domains after energy minimization and the<br>simulation broke afterall.<br> <br>With one protein + 10 ligand + water molecules, ( 6 x 6 x 6 )<br>There is no problems like that.</div>
<div>Please give me your ideas to solve the problem.<br>The commands are listed below and the .tpr file created by grompp is attached.<br> <br>Thank you<br>Lin<br> <br> <br> <br>1. pdb2gmx_mpi -f 6LYZ.pdb -o 6LYZ.gro -p 6LYZ.top      =&gt; G 45a3 <br>
2. Energy minimization of the structure (vacuum)<br> pbc = no,<br>grompp_mpi -np 16 -v -f minim.mdp -c 6LYZ.gro -p 6LYZ.top -o 6LYZ-EM-vacuum.tpr<br>mpiexec -np 16 mdrun_mpi -v -deffnm 6LYZ-EM-vacuum<br> <br> <br>3. Periodic boundary conditions<br>
editconf_mpi -f 6LYZ-EM-vacuum.gro -o 6LYZ-PBC.gro -bt cubic -d 0.75 -box 7.0 7.0 7.0 <br> <br>4. Add another 20 ligands randomly into the simulation (nm^3) box<br>genbox_mpi -seed 201 -cp 6LYZ-PBC.gro -ci ligand.gro -nmol 20 -p 6LYZ.top -o 6LYZ20ligand.gro<br>
 <br>6. Solvent addition<br>genbox_mpi -cp 6LYZ20ligand.gro -cs spc216.gro -p 6LYZ.top -o 6LYZ-water.gro<br> <br>7. Addition of ions: counter charge and concentration<br>grompp_mpi -v -f minim.mdp -c 6LYZ-water.gro -p 6LYZ.top -o 6LYZ-water.tpr <br>
genion_mpi -s 6LYZ-water.tpr -o 6LYZ-solvated.gro -nn 28 -nname CL- <br> <br>8. Energy minimization of the solvated system<br>pbc = xyz (minim.mdp)<br>grompp_mpi -np 16 -v -f minim.mdp -c 6LYZ-solvated.gro -p 6LYZ.top -o 6LYZ-EM-solvated  <br>
mpiexec -np 16 mdrun_mpi -v -deffnm 6LYZ-EM-solvated <br> <br> </div>
<div>Reading file 6LYZ-EM-solvated.tpr, VERSION 3.3.3 (single precision)<br>Reading file 6LYZ-EM-solvated.tpr, VERSION 3.3.3 (single precision)<br>6LYZ-EM-solvated.tpr:<br>   header:<br>      bIr    = present<br>      bBox   = present<br>
      bTop   = present<br>      bX     = present<br>      bV     = present<br>      bF     = not present<br>      natoms = 33042<br>      step   = 0<br>      t      = 0.000000e+00<br>      lambda = 0.000000e+00<br>   ir:<br>
      integrator           = steep<br>      nsteps               = 50000<br>      init_step            = 0<br>      ns_type              = Simple<br>      nstlist              = 5<br>      ndelta               = 2<br>      bDomDecomp           = FALSE<br>
      decomp_dir           = 0<br>      nstcomm              = 1<br>      comm_mode            = Linear<br>      nstcheckpoint        = 1000<br>      nstlog               = 100<br>      nstxout              = 100<br>      nstvout              = 100<br>
      nstfout              = 0<br>      nstenergy            = 1<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                 = xyz<br>      bUncStart            = FALSE<br>      bShakeSOR            = FALSE<br>      etc                  = No<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                = 1<br>      coulombtype          = Cut-off<br>      rcoulomb_switch      = 0<br>      rcoulomb             = 1<br>      vdwtype              = Cut-off<br>
      rvdw_switch          = 0<br>      rvdw                 = 1<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             = 0<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               = 1<br>      niter                = 20<br>      fc_stepsize          = 0<br>      nstcgsteep           = 1000<br>
      nbfgscorr            = 10<br>      ConstAlg             = Lincs<br>      shake_tol            = 0.0001<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:            99123<br>      ref_t:               0<br>      tau_t:               0<br>anneal:                   No<br>
ann_npoints:               0<br>      acc:                 0           0           0<br>      nfreeze:           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>   box (3x3):<br>      box[    0]={ 7.00000e+00,  0.00000e+00,  0.00000e+00}<br>      box[    1]={ 0.00000e+00,  7.00000e+00,  0.00000e+00}<br>
      box[    2]={ 0.00000e+00,  0.00000e+00,  7.00000e+00}<br>   boxv (3x3):<br>      boxv[    0]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}<br>      boxv[    1]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}<br>      boxv[    2]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}<br>
   pcoupl_mu (3x3):<br>      pcoupl_mu[    0]={ 1.00000e+00,  0.00000e+00,  0.00000e+00}<br>      pcoupl_mu[    1]={ 0.00000e+00,  1.00000e+00,  0.00000e+00}<br>      pcoupl_mu[    2]={ 0.00000e+00,  0.00000e+00,  1.00000e+00}<br>
   nosehoover_xi:                  0<br>   x (33042x3):<br>      x[    0]={ 3.88200e+00,  2.44200e+00,  2.61100e+00}<br>      x[    1]={ 3.87900e+00,  2.34300e+00,  2.62700e+00}<br>      x[    2]={ 3.97600e+00,  2.47000e+00,  2.59300e+00}<br>
      x[    3]={ 3.85000e+00,  2.49000e+00,  2.69300e+00}<br>      x[    4]={ 3.79500e+00,  2.47800e+00,  2.49600e+00}<br>      x[    5]={ 3.65000e+00,  2.43700e+00,  2.52700e+00}<br>      x[    6]={ 3.55300e+00,  2.46400e+00,  2.41200e+00}<br>
      x[    7]={ 3.41000e+00,  2.42200e+00,  2.44600e+00}<br></div>