[gmx-users] Gromacs versions 4.0.5 and 4.5.4

Sapna Sarupria sapna.sarupria at gmail.com
Thu Oct 20 00:26:49 CEST 2011


Hi Itamar and Mark,

The error message is pasted below. I tried both running minimization and
then running the MD; and using a configuration from a previous simulation
(that was run using Gromacs 4.0.5). In both these case the simulations are
crashing. The error message is similar.

Mark, Yes there is no reason as such to have TIP and SOL defined but it is
for the purpose of my simulations. It helps me differentiate between water
phases at the beginning of the simulation (SOL is in solid and TIP is in
liquid phase). Indeed, they are exactly the same, as they are supposed to
be.

I also tried using the Berendsen coupling for both temperature and pressure,
but the simulations still crash. Like I mentioned, all of these simulations
work perfectly in 4.0.5 Gromacs version with Nose-Hoover and PR starting
from the exact same configuration (except initial velocity) that I am using
in 4.5 version.

Thank you all for your suggestions and help.

Sapna.

@@@@ Error Message from Gromacs @@@@

starting mdrun 'Hydrate with cages filled with carbon dioxide'
15000000 steps,  30000.0 ps.
step 0Inner product between old and new vector <= 0.0!
constraint #1 atoms 25869 and 25871
Wrote pdb files with previous and current coordinates
Inner product between old and new vector <= 0.0!
constraint #1 atoms 145 and 147
Wrote pdb files with previous and current coordinates
Segmentation fault

@@@@@



On Wed, Oct 19, 2011 at 6:19 PM, Mark Abraham <Mark.Abraham at anu.edu.au>wrote:

>  On 20/10/2011 8:40 AM, Sapna Sarupria wrote:
>
> Hello,
>
>  I did change nsttcouple and nstpcouple but the simulations that run in
> 4.0.5 are still crashing in 4.5.4. I think it is related to constraints but
> I am unable to figure out exactly what is different. I have pasted both my
> topology and mdp (updated for 4.5.4) files. Any ideas? I have read through
> the manual and it seems like the mdp files does not need any changes, but
> perhaps I am missing something.
>
>
> P-R P-coupling is not well-suited to equilibration if you are not close to
> equilibrium. Since you are generating velocities, you are likely not close
> to equilibrium.
>
> I don't see that it is causing a problem, but there is no reason to have
> both SOL and TIP molecule type. They're identical.
>
> Mark
>
>
>
>  Thank you for your help!
>
>  Sincerely,
> Sapna
>
>  @@@@ MDP File @@@@
>  title               =  100% occupancy CO2 hydrate ; a string
> cpp               =  /lib/cpp                 ; c-preprocessor
> integrator        = md
> dt                  =  0.002                    ; time step
> nsteps           =  15000000                 ; number of steps
> nstcomm       =  10                       ; reset c.o.m. motion
> nstxout           =  0000                    ; write coords
> nstvout           =  0000                    ; write velocities
>  nstlog             =  25000                    ; print to logfile
> nstenergy       =  500                      ; print energies
> xtc_grps         =  OW_HW1_HW2_CO2
> nstxtcout        =  1000
> nstlist             =  10                       ; update pairlist
> ns_type            =  grid                     ; pairlist method
> coulombtype    =  PME
> rvdw                =  1.2                      ; cut-off for vdw
> rcoulomb         =  1.2                      ; cut-off for coulomb
> rlist                  =  1.2                      ; cut-off for coulomb
> DispCorr         =  EnerPres
> Tcoupl             =  Nose-Hoover
> ref_t                 = 270
> tc-grps             =  System
> tau_t                 =  0.5
> nsttcouple          =  1
> Pcoupl              =  Parrinello-Rahman
> Pcoupltype        =  semiisotropic            ; pressure geometry
> tau_p                  =  1.0   1.0                ; p-coupoling time
> compressibility   =  4.5e-5  4.5e-5           ; compressibility
> ref_p                   =  30.5  30.5               ; ref pressure
> nstpcouple          =  1
> gen_vel               =  yes                      ; generate initial vel
> gen_temp            =  260                      ; initial temperature
> gen_seed             =  372340                   ; random seed
> constraint_algorithm = shake
> constraints         =  all-bonds
>  @@@@ end MDP File @@@@
>
>  @@@@ Topology file @@@@
>
>  [ defaults ]
> ; nbfunc        comb-rule       gen-pairs       fudgeLJ fudgeQQ
>   1             2               no              1.0     1.0
>
>  [ atomtypes ]
> ; name      mass      charge    ptype         sigma       epsilon
> ; Water parameters are those of Vega TIP4P/Ice Model
>  OWT4     15.9994      0.0000    A          0.31668     0.882164429
>   HW        1.008          0.5897    A          0.000       0.000
>   MW        0.000         -1.1794    V          0.000       0.000
>
>
>  ; TraPPE  rigid
>   M2      22.0000       0.00      A          0.000      0.000000 ;
>   M1      22.0000       0.00      A          0.000      0.000000 ;
>   DO      00.0000      -0.35      V          0.305      0.656806 ; oxygen
>   DC      00.0000       0.70      V    0.280      0.224478 ; carbon
>
>
>  [ moleculetype ]
> ; molname  nrexcl
>   SOL       2
>
>  [ atoms ]
> 1       OWT4      1      SOL      OW     1       0.0000
> 2         HW      1       SOL     HW1     1       0.5897
> 3         HW      1       SOL     HW2     1       0.5897
> 4         MW      1       SOL      MW     1      -1.1794
>
>  [ bonds ]
> ; i j funct length force.c.
> 1 2 1   0.09572     502416.0
> 1 3 1        0.09572     502416.0
> 2       3       1       0.15139     502416.0
>
>  [ exclusions ]
> 1    2    3     4
> 2    1    3     4
> 3    1    2     4
> 4    1    2     3
>
>  ; The position of the dummy is computed as follows:
> ;
> ; O
> ;
> ;     D
> ;
> ; H H
> ;
> ; const = distance (OD) / [ cos (angle(DOH)) * distance (OH) ]
> ;  0.01577 nm / [ cos (52.26 deg) * 0.09572 nm ]
>
>  ; Dummy pos x4 = x1 + a*(x2-x1) + b*(x3-x1)
>
>  [ virtual_sites3 ]
> ; Dummy from funct a b
> 4 1 2 3 1 0.13458335087   0.13458335087
>
>  [ moleculetype ]
> ; molname  nrexcl
>   TIP       2
>
>  [ atoms ]
> 1       OWT4      1     TIP      OW     1       0.0000
> 2         HW      1       TIP     HW1     1       0.5897
> 3         HW      1       TIP     HW2     1       0.5897
> 4         MW      1       TIP      MW     1      -1.1794
>
>  [ bonds ]
> ; i j funct length force.c.
> 1 2 1   0.09572     502416.0
> 1 3 1        0.09572     502416.0
> 2       3       1       0.15139     502416.0
>
>  [ exclusions ]
> 1    2    3     4
> 2    1    3     4
> 3    1    2     4
> 4    1    2     3
>
>  [ virtual_sites3 ]
> ; Dummy from funct a b
> 4 1 2 3 1 0.13458335087   0.13458335087
>
>
>  [ moleculetype ]
> ; molname  nrexcl
>   CO2    2
>
>  [ atoms ]
> 1         M1      1       CO2      M1      1       0.00    22.00
>  2         M2      1       CO2      M2      1       0.00    22.00
> 3         DC      1       CO2      CO      1       0.70    0.000
> 4         DO      1       CO2      OC1     1      -0.35    0.000
>  5         DO      1       CO2      OC2     1      -0.35    0.000
>
>
>  [ constraints ]
> 1    2      1    0.19785026
>
>
>  [ virtual_sites2 ]
> ; ai     aj     ak    funct    a
>   3      1      2     1       0.50
>   4      1      2     1      -0.086327900
>   5      1      2     1       1.086327913
>
>  [ exclusions ]
> 3       4       5
> 4       5       3
> 5       4       3
>
>  [ system ]
> Hydrate with cages filled with carbon dioxide
>
>  [ molecules ]
>  SOL    2944
> CO2    512
> TIP    3641
>
>  @@@@ End topology file @@@@
>
>
>
>
> --
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-- 
Sapna Sarupria
Post-doctoral Researcher
Princeton University
New Jersey 08540
U.S.A.

Life isn't about finding yourself. Life is about creating yourself. --
George Bernard Shaw.
Dare to Dream
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