[gmx-users] double precision energy minimization show zero pressure in gromacs 4.5.5

Yongchul Chung yxc169 at case.edu
Thu Apr 26 17:00:09 CEST 2012


Hi all,

I am carrying out energy minimization on bulk polymer system (N~20000) with
integrator = l-bfgs in double precision gromacs 4.5.5.  I am using
tabulated force-fields for bonded, and non-bonded interactions. In the
force field, the coulombic interaction is set to zero, hence, the output is
zero in md.log file.

I used g_energy to check the energy and pressure of the system after the
minimization is finished. For some reason, the pressure output for the
system is 0 with gromacs 4.5.5. So I went back and checked the md.log file
to see if this happens during the simulation or not, and I found at time =
0, the pressure is 0.

I wanted to make sure that this has to do with gromacs version, and not how
the mdp file is configured, so I did same minimization with gromacs 4.0.7.
When using version 4.0.7 with the same input files, I get the pressure
output just fine. The potential energy at the end of simulation for both
cases are exactly the same (only difference is 4.0.7 converges at 1754
steps, and 4.5.5 converges at 2148 steps)

It is possible that I am doing (or setting) something wrong since I'm using
the same mdp file from 4.0.7 to 4.5.5. To check if I'm setting something
wrong by default, I compared the md.log output between these two versions.
It seems like there are a few new things with gromacs 4.5.5 that is missing
in 4.0.7. For example, with 4.5.5

nstcalcenergy = -1
nstcouple = -1
nstpcouple = -1
rlistlong = 1.1

I see nstcalcenergy is the frequency of energy output during calculation so
it does not affect any calculation. Also since I am not coupling my system
to thermal/pressure bath, nstcouple, nspcouple, and rlistlong does not mean
much here.

So I suppose I can repeat the calculation again with 4.0.7 instead. But
since I've already carried out lots of calculation with 4.5.5, I kind of do
not want to repeat the steps again in calculating pressure values, if
possible. If someone can help me with this, it would be great.

I am appending snippet of md.log output from 4.5.5 and 4.0.7 below as a
reference.

Greg

### md.log file 4.5.5 ###

:-)  /nfs/01/cwr0351/GMX4.5.5/bin/mdrun_d (double precision)  (-:


++++ PLEASE READ AND CITE THE FOLLOWING REFERENCE ++++
B. Hess and C. Kutzner and D. van der Spoel and E. Lindahl
GROMACS 4: Algorithms for highly efficient, load-balanced, and scalable
molecular simulation
J. Chem. Theory Comput. 4 (2008) pp. 435-447
-------- -------- --- Thank You --- -------- --------


++++ PLEASE READ AND CITE THE FOLLOWING REFERENCE ++++
D. van der Spoel, E. Lindahl, B. Hess, G. Groenhof, A. E. Mark and H. J. C.
Berendsen
GROMACS: Fast, Flexible and Free
J. Comp. Chem. 26 (2005) pp. 1701-1719
-------- -------- --- Thank You --- -------- --------


++++ PLEASE READ AND CITE THE FOLLOWING REFERENCE ++++
E. Lindahl and B. Hess and D. van der Spoel
GROMACS 3.0: A package for molecular simulation and trajectory analysis
J. Mol. Mod. 7 (2001) pp. 306-317
-------- -------- --- Thank You --- -------- --------


++++ PLEASE READ AND CITE THE FOLLOWING REFERENCE ++++
H. J. C. Berendsen, D. van der Spoel and R. van Drunen
GROMACS: A message-passing parallel molecular dynamics implementation
Comp. Phys. Comm. 91 (1995) pp. 43-56
-------- -------- --- Thank You --- -------- --------

Input Parameters:
   integrator           = l-bfgs
   nsteps               = 100000
   init_step            = 0
   ns_type              = Grid
   nstlist              = 10
   ndelta               = 2
   nstcomm              = 100
   comm_mode            = Linear
   nstlog               = 1
   nstxout              = 1
   nstvout              = 1
   nstfout              = 1
   nstcalcenergy        = -1
   nstenergy            = 1
   nstxtcout            = 10
   init_t               = 0
   delta_t              = 0.003
   xtcprec              = 1000
   nkx                  = 0
   nky                  = 0
   nkz                  = 0
   pme_order            = 4
   ewald_rtol           = 1e-05
   ewald_geometry       = 0
   epsilon_surface      = 0
   optimize_fft         = FALSE
   ePBC                 = xyz
   bPeriodicMols        = FALSE
   bContinuation        = TRUE
   bShakeSOR            = FALSE
   etc                  = No
   nsttcouple           = -1
   epc                  = No
   epctype              = Isotropic
   nstpcouple           = -1
   tau_p                = 5
   ref_p (3x3):
      ref_p[    0]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      ref_p[    1]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      ref_p[    2]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
   compress (3x3):
      compress[    0]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      compress[    1]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      compress[    2]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
   refcoord_scaling     = No
   posres_com (3):
      posres_com[0]= 0.00000e+00
      posres_com[1]= 0.00000e+00
      posres_com[2]= 0.00000e+00
   posres_comB (3):
      posres_comB[0]= 0.00000e+00
      posres_comB[1]= 0.00000e+00
      posres_comB[2]= 0.00000e+00
   andersen_seed        = -1
   rlist                = 1.1
   rlistlong            = 1.1
   rtpi                 = 0.05
   coulombtype          = User
   rcoulomb_switch      = 0
   rcoulomb             = 1
   vdwtype              = User
   rvdw_switch          = 0
   rvdw                 = 1
   epsilon_r            = 1
   epsilon_rf           = 1
   tabext               = 1
   implicit_solvent     = No
   gb_algorithm         = Still
   gb_epsilon_solvent   = 80
   nstgbradii           = 1
   rgbradii             = 2
   gb_saltconc          = 0
   gb_obc_alpha         = 1
   gb_obc_beta          = 0.8
   gb_obc_gamma         = 4.85
   gb_dielectric_offset = 0.009
   sa_algorithm         = Ace-approximation
   sa_surface_tension   = 2.05016
   DispCorr             = No
   free_energy          = no
   init_lambda          = 0
   delta_lambda         = 0
   n_foreign_lambda     = 0
   sc_alpha             = 0
   sc_power             = 0
   sc_sigma             = 0.3
   sc_sigma_min         = 0.3
   nstdhdl              = 10
   separate_dhdl_file   = yes
   dhdl_derivatives     = yes
   dh_hist_size         = 0
   dh_hist_spacing      = 0.1
   nwall                = 0
   wall_type            = 9-3
   wall_atomtype[0]     = -1
   wall_atomtype[1]     = -1
   wall_density[0]      = 0
   wall_density[1]      = 0
   wall_ewald_zfac      = 3
   pull                 = no
   disre                = No
   disre_weighting      = Conservative
   disre_mixed          = FALSE
   dr_fc                = 1000
   dr_tau               = 0
   nstdisreout          = 100
   orires_fc            = 0
   orires_tau           = 0
   nstorireout          = 100
   dihre-fc             = 1000
   em_stepsize          = 0.01
   em_tol               = 1e-10
   niter                = 20
   fc_stepsize          = 0
   nstcgsteep           = 1000000
   nbfgscorr            = 10
   ConstAlg             = Lincs
   shake_tol            = 0.0001
   lincs_order          = 4
   lincs_warnangle      = 30
   lincs_iter           = 1
   bd_fric              = 0
   ld_seed              = 1993
   cos_accel            = 0
   deform (3x3):
      deform[    0]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      deform[    1]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      deform[    2]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
   userint1             = 0
   userint2             = 0
   userint3             = 0
   userint4             = 0
   userreal1            = 0
   userreal2            = 0
   userreal3            = 0
   userreal4            = 0
grpopts:
   nrdf:       57597
   ref_t:           0
   tau_t:           0
anneal:          No
ann_npoints:           0
   acc:	           0           0           0
   nfreeze:           N           N           N
   energygrp_flags[  0]: 2 2
   energygrp_flags[  1]: 2 2
   efield-x:
      n = 0
   efield-xt:
      n = 0
   efield-y:
      n = 0
   efield-yt:
      n = 0
   efield-z:
      n = 0
   efield-zt:
      n = 0
   bQMMM                = FALSE
   QMconstraints        = 0
   QMMMscheme           = 0
   scalefactor          = 1
qm_opts:
   ngQM                 = 0
Table routines are used for coulomb: TRUE
Table routines are used for vdw:     TRUE
Cut-off's:   NS: 1.1   Coulomb: 1   LJ: 1
System total charge: 0.000
Read user tables from table_A_A.xvg with 501 data points.
Tabscale = 50 points/nm
Read user tables from table_A_B.xvg with 501 data points.
Tabscale = 50 points/nm
Read user tables from table_B_B.xvg with 501 data points.
Tabscale = 50 points/nm
Read user tables from table_b0.xvg with 2501 data points.
Tabscale = 500 points/nm
Read user tables from table_b1.xvg with 2501 data points.
Tabscale = 500 points/nm
Read user tables from table_b5.xvg with 2501 data points.
Tabscale = 500 points/nm
Read user tables from table_b12.xvg with 2496 data points.
Tabscale = 500 points/nm
Read user tables from table_b17.xvg with 2496 data points.
Tabscale = 500 points/nm
Read user tables from table_b19.xvg with 2501 data points.
Tabscale = 500 points/nm
Read user tables from table_b40.xvg with 2496 data points.
Tabscale = 500 points/nm
Read user tables from table_a1.xvg with 901 data points.
Read user tables from table_a2.xvg with 901 data points.
Read user tables from table_a3.xvg with 901 data points.
Read user tables from table_a4.xvg with 181 data points.
Read user tables from table_a5.xvg with 181 data points.
Read user tables from table_d6.xvg with 181 data points.
Read user tables from table_d7.xvg with 181 data points.
Read user tables from table_d8.xvg with 181 data points.
Read user tables from table_d9.xvg with 181 data points.
Configuring nonbonded kernels...
Configuring standard C nonbonded kernels...
Testing x86_64 SSE2 support... present.


Initiating Low-Memory BFGS Minimizer
Max number of connections per atom is 14
Total number of connections is 267000
Max number of graph edges per atom is 2
Total number of graph edges is 38300
Started Low-Memory BFGS Minimizer on node 0 Tue Apr 24 17:03:47 2012

Low-Memory BFGS Minimizer:
   Tolerance (Fmax)   =  1.00000e-10
   Number of steps    =       100000
Grid: 12 x 12 x 12 cells
           Step           Time         Lambda
              0        0.00000        0.00000

   Energies (kJ/mol)
     Tab. Bonds  Tab. Bonds NC    Tab. Angles      Tab. Dih.        LJ (SR)
    4.13987e+03    3.14441e+04    2.31911e+04    3.37997e+04   -1.62435e+05
   Coulomb (SR)      Potential Pressure (bar)
    0.00000e+00   -6.98604e+04    0.00000e+00

Using 10 BFGS correction steps.

   F-max             =  2.17837e-01 on atom 15319
   F-Norm            =  3.37657e-02

           Step           Time         Lambda
              0        0.00000        0.00000

   Energies (kJ/mol)
     Tab. Bonds  Tab. Bonds NC    Tab. Angles      Tab. Dih.        LJ (SR)
    4.13987e+03    3.14441e+04    2.31911e+04    3.37997e+04   -1.62435e+05
   Coulomb (SR)      Potential Pressure (bar)
    0.00000e+00   -6.98604e+04    0.00000e+00

### md.log for 4.0.7 ###

 :-)  /nfs/01/cwr0351/local_GMX4.0.7_d/bin/mdrun_d_mpi (double precision)  (-:


++++ PLEASE READ AND CITE THE FOLLOWING REFERENCE ++++
B. Hess and C. Kutzner and D. van der Spoel and E. Lindahl
GROMACS 4: Algorithms for highly efficient, load-balanced, and scalable
molecular simulation
J. Chem. Theory Comput. 4 (2008) pp. 435-447
-------- -------- --- Thank You --- -------- --------


++++ PLEASE READ AND CITE THE FOLLOWING REFERENCE ++++
D. van der Spoel, E. Lindahl, B. Hess, G. Groenhof, A. E. Mark and H. J. C.
Berendsen
GROMACS: Fast, Flexible and Free
J. Comp. Chem. 26 (2005) pp. 1701-1719
-------- -------- --- Thank You --- -------- --------


++++ PLEASE READ AND CITE THE FOLLOWING REFERENCE ++++
E. Lindahl and B. Hess and D. van der Spoel
GROMACS 3.0: A package for molecular simulation and trajectory analysis
J. Mol. Mod. 7 (2001) pp. 306-317
-------- -------- --- Thank You --- -------- --------


++++ PLEASE READ AND CITE THE FOLLOWING REFERENCE ++++
H. J. C. Berendsen, D. van der Spoel and R. van Drunen
GROMACS: A message-passing parallel molecular dynamics implementation
Comp. Phys. Comm. 91 (1995) pp. 43-56
-------- -------- --- Thank You --- -------- --------

Input Parameters:
   integrator           = l-bfgs
   nsteps               = 100000
   init_step            = 0
   ns_type              = Grid
   nstlist              = 10
   ndelta               = 2
   nstcomm              = 100
   comm_mode            = Linear
   nstlog               = 1
   nstxout              = 1
   nstvout              = 1
   nstfout              = 1
   nstenergy            = 1
   nstxtcout            = 10
   init_t               = 0
   delta_t              = 0.003
   xtcprec              = 1000
   nkx                  = 0
   nky                  = 0
   nkz                  = 0
   pme_order            = 4
   ewald_rtol           = 1e-05
   ewald_geometry       = 0
   epsilon_surface      = 0
   optimize_fft         = FALSE
   ePBC                 = xyz
   bPeriodicMols        = FALSE
   bContinuation        = TRUE
   bShakeSOR            = FALSE
   etc                  = No
   epc                  = No
   epctype              = Isotropic
   tau_p                = 5
   ref_p (3x3):
      ref_p[    0]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      ref_p[    1]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      ref_p[    2]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
   compress (3x3):
      compress[    0]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      compress[    1]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      compress[    2]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
   refcoord_scaling     = No
   posres_com (3):
      posres_com[0]= 0.00000e+00
      posres_com[1]= 0.00000e+00
      posres_com[2]= 0.00000e+00
   posres_comB (3):
      posres_comB[0]= 0.00000e+00
      posres_comB[1]= 0.00000e+00
      posres_comB[2]= 0.00000e+00
   andersen_seed        = -1
   rlist                = 1.1
   rtpi                 = 0.05
   coulombtype          = User
   rcoulomb_switch      = 0
   rcoulomb             = 1
   vdwtype              = User
   rvdw_switch          = 0
   rvdw                 = 1
   epsilon_r            = 1
   epsilon_rf           = 1
   tabext               = 1
   implicit_solvent     = No
   gb_algorithm         = Still
   gb_epsilon_solvent   = 80
   nstgbradii           = 1
   rgbradii             = 2
   gb_saltconc          = 0
   gb_obc_alpha         = 1
   gb_obc_beta          = 0.8
   gb_obc_gamma         = 4.85
   sa_surface_tension   = 2.092
   DispCorr             = No
   free_energy          = no
   init_lambda          = 0
   sc_alpha             = 0
   sc_power             = 0
   sc_sigma             = 0.3
   delta_lambda         = 0
   nwall                = 0
   wall_type            = 9-3
   wall_atomtype[0]     = -1
   wall_atomtype[1]     = -1
   wall_density[0]      = 0
   wall_density[1]      = 0
   wall_ewald_zfac      = 3
   pull                 = no
   disre                = No
   disre_weighting      = Conservative
   disre_mixed          = FALSE
   dr_fc                = 1000
   dr_tau               = 0
   nstdisreout          = 100
   orires_fc            = 0
   orires_tau           = 0
   nstorireout          = 100
   dihre-fc             = 1000
   em_stepsize          = 0.01
   em_tol               = 1e-10
   niter                = 20
   fc_stepsize          = 0
   nstcgsteep           = 1000000
   nbfgscorr            = 10
   ConstAlg             = Lincs
   shake_tol            = 0.0001
   lincs_order          = 4
   lincs_warnangle      = 30
   lincs_iter           = 1
   bd_fric              = 0
   ld_seed              = 1993
   cos_accel            = 0
   deform (3x3):
      deform[    0]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      deform[    1]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
      deform[    2]={ 0.00000e+00,  0.00000e+00,  0.00000e+00}
   userint1             = 0
   userint2             = 0
   userint3             = 0
   userint4             = 0
   userreal1            = 0
   userreal2            = 0
   userreal3            = 0
   userreal4            = 0
grpopts:
   nrdf:       57597
   ref_t:           0
   tau_t:           0
anneal:          No
ann_npoints:           0
   acc:	           0           0           0
   nfreeze:           N           N           N
   energygrp_flags[  0]: 2 2
   energygrp_flags[  1]: 2 2
   efield-x:
      n = 0
   efield-xt:
      n = 0
   efield-y:
      n = 0
   efield-yt:
      n = 0
   efield-z:
      n = 0
   efield-zt:
      n = 0
   bQMMM                = FALSE
   QMconstraints        = 0
   QMMMscheme           = 0
   scalefactor          = 1
qm_opts:
   ngQM                 = 0
Table routines are used for coulomb: TRUE
Table routines are used for vdw:     TRUE
Cut-off's:   NS: 1.1   Coulomb: 0   LJ: 1
System total charge: 0.000
Read user tables from table_A_A.xvg with 501 data points.
Tabscale = 50 points/nm
Read user tables from table_A_B.xvg with 501 data points.
Tabscale = 50 points/nm
Read user tables from table_B_B.xvg with 501 data points.
Tabscale = 50 points/nm
Read user tables from table_b0.xvg with 2501 data points.
Tabscale = 500 points/nm
Read user tables from table_b1.xvg with 2501 data points.
Tabscale = 500 points/nm
Read user tables from table_b5.xvg with 2501 data points.
Tabscale = 500 points/nm
Read user tables from table_b12.xvg with 2496 data points.
Tabscale = 500 points/nm
Read user tables from table_b17.xvg with 2496 data points.
Tabscale = 500 points/nm
Read user tables from table_b19.xvg with 2501 data points.
Tabscale = 500 points/nm
Read user tables from table_b40.xvg with 2496 data points.
Tabscale = 500 points/nm
Read user tables from table_a1.xvg with 901 data points.
Read user tables from table_a2.xvg with 901 data points.
Read user tables from table_a3.xvg with 901 data points.
Read user tables from table_a4.xvg with 181 data points.
Read user tables from table_a5.xvg with 181 data points.
Read user tables from table_d6.xvg with 181 data points.
Read user tables from table_d7.xvg with 181 data points.
Read user tables from table_d8.xvg with 181 data points.
Read user tables from table_d9.xvg with 181 data points.
Configuring nonbonded kernels...
Testing x86_64 SSE2 support... present.


Initiating Low-Memory BFGS Minimizer
Max number of connections per atom is 11
Total number of connections is 209800
Max number of graph edges per atom is 2
Total number of graph edges is 38300
Started Low-Memory BFGS Minimization on node 0 Thu Apr 26 10:10:05 2012
Low-Memory BFGS Minimizer:
   Tolerance (Fmax)   =  1.00000e-10
   Number of steps    =       100000
Grid: 12 x 12 x 12 cells
           Step           Time         Lambda
              0        0.00000        0.00000

   Energies (kJ/mol)
     Tab. Bonds  Tab. Bonds NC    Tab. Angles      Tab. Dih.        LJ (SR)
    4.13987e+03    3.14441e+04    2.31911e+04    3.37997e+04   -1.62435e+05
   Coulomb (SR)      Potential Pressure (bar)
    0.00000e+00   -6.98604e+04   -5.12822e+02

Using 10 BFGS correction steps.

   F-max             =  2.17837e-01 on atom 15319
   F-Norm            =  3.37657e-02

           Step           Time         Lambda
              0        0.00000        0.00000

   Energies (kJ/mol)
     Tab. Bonds  Tab. Bonds NC    Tab. Angles      Tab. Dih.        LJ (SR)
    4.13987e+03    3.14441e+04    2.31911e+04    3.37997e+04   -1.62435e+05
   Coulomb (SR)      Potential Pressure (bar)
    0.00000e+00   -6.98604e+04   -5.12824e+02
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