[gmx-users] Reg: Running Energy minimisation for dichloroethane (DCE)

vinothkumar mohanakrishnan kmvinoth at gmail.com
Thu Oct 21 13:52:49 CEST 2010


Hi Justin

Below is my nvt.mdp (nvt equilibration) file.i think probably you can have
look at it and its not such big.

define          =                 -DFLEXIBLE
integrator     =                  md
nsteps         =                  50000
dt                =                  0.002
nstxout        =                  100
nstvout        =                  100
nstenergy    =                  100
nstlog         =                  100
constraint_algorithm     = shake
constraints        =            none
unconstrained_start    =    yes
shake_tol        =              0.0001
morse            =               no
ns_type        =                grid
nstlist        =                   5
rlist        =                      1.0
coulombtype    =            PME
rcoulomb    =                  1.0
vdwtype        =               Cut-off
rvdw        =                    1.0
pme_order    =                4
fourierspacing    =          0.16
pbc        =                     xyz
tcoupl        =                 V-rescale
tc-grps        =                system
tau_t        =                   0.1
ref_t        =                   300
DispCorr    =                 Ener
gen_vel        =              yes
gen_temp    =               300
gen_seed    =               173529

regarding the plot i too know that one should use Xmgrace to plot. In the
pressure Vs time(lysozyme tutorial) you have got two graphs. i to got the
pressure Vs time (black line graph) my question is how to get the running
average ( red line) and plot?. does i need any command to get the running
average?. any help is highly appreciated.

Regards
Vinoth

On Thu, Oct 21, 2010 at 4:56 PM, Justin A. Lemkul <jalemkul at vt.edu> wrote:

>
>
> vinothkumar mohanakrishnan wrote:
>
>> Hi justin
>>
>> I found what went wrong and i corrected my mdp file.now the system
>> equilibrated to the desired temperature 300 K (plus r minus 30 K) is this
>> ok?
>>
>
> This is impossible to assess without seeing your .mdp settings.  A
> fluctuation of 10% is probably fine.
>
>
>  Apart from that i want to know how you plot the average running pressure
>> and density in your tutorial for lyzosyme (redline). i just  want to do that
>> for DCE. any help is highly appreciated.
>>
>>
> Xmgrace.
>
> -Justin
>
>  Regards
>> Vinoth
>>
>>
>> On Wed, Oct 20, 2010 at 5:33 PM, Justin A. Lemkul <jalemkul at vt.edu<mailto:
>> jalemkul at vt.edu>> wrote:
>>
>>
>>
>>    vinothkumar mohanakrishnan wrote:
>>
>>        Hi Justin
>>
>>        I corrected the mistake what you said and i am able to run
>>        energy minimisation and equilibration. but when i view my em.gro
>>        and equilibration.gro in VMD it seems to me that the bonds
>>        between the atoms are broken in molecules.I used g_energy to
>>        check weather the system has
>>
>>
>>    VMD tries to guess where bonds should be, but does not always do a
>>    good job. Your topology defines bonds.  These are the only bonds
>>    that there will be.  None can be broken or formed in standard MD.
>>
>>
>>        equilibrated to the required temperature (300K) i found that the
>>        variation in the temperature was 100K (plus r minus) . i am not
>>        able find out what went wrong. any help is highly appreciated.
>>
>>
>>    Without seeing your .mdp file, there's no way to know.  The
>>    fluctuation does seem too high, though, unless your system really is
>>    just that unstable.  Are other properties converged - potential
>>    energy, density, etc?  What type of ensemble are you using?
>>
>>    -Justin
>>
>>        Regards
>>        Vinoth
>>
>>
>>        On Mon, Oct 18, 2010 at 6:09 PM, Justin A. Lemkul
>>        <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>>        <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>> wrote:
>>
>>
>>
>>           vinothkumar mohanakrishnan wrote:
>>
>>               Dear Justin
>>
>>               what corrections i should make to ffoplsaan.itp to make it
>>               correct. what i should give instead of CAB and CLAA?.
>>
>>
>>           You must use atom types, not names.  Unfortunately, you've
>>        chosen to
>>           use atom names, which are also types, which makes all of this
>>        quite
>>           confusing if you're not sure what you're doing.
>>
>>           You defined two new atom types - opls_966 (CAB) and opls_967
>>        (CLAA),
>>           which are the only indicators you are allowed to use if
>>        introducing
>>           new types.  Thus, references to atom names (CAC, CLAD) will
>>        generate
>>           fatal errors.
>>
>>
>>               i copied the .rtp .atp .itp files from
>>               usr/local/gromacs/share/gromacs/top to my working
>>        directory and
>>               added these parameters to the corresponding files. what
>>        you mean
>>               is should i need to add these parameters to the source
>>        directory
>>               ( usr/local/gromacs/share/gromacs/top)?
>>
>>
>>           Your topology needs to be consistent with whatever files need
>>        to be
>>           included. By default, Gromacs checks the working directory
>> first,
>>           but if you've moved to a new (sub)directory to carry out further
>>           steps, the grompp will not find your modified files, but will
>>           instead locate only the default force field files in $GMXLIB.
>>            Either keep all your work in one directory (which can get
>>        messy),
>>           or make use of the "include" keyword in the .mdp file.  Any
>>           directory specified there will be searched after the working
>>           directory, but before $GMXLIB.
>>
>>           -Justin
>>
>>               Regards
>>               Vinoth
>>
>>
>>               On Mon, Oct 18, 2010 at 5:27 PM, Justin A. Lemkul
>>               <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>>        <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>>               <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>>        <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>> wrote:
>>
>>
>>
>>                  vinothkumar mohanakrishnan wrote:
>>
>>                      Hi all
>>
>>                      i added new atomtype for dichloroethane (DCE) and
>>        added the
>>                      corresponding parameters in the .rtp, .atp,
>>        .bon.itp, .nb.itp
>>                      respectively. given below are my additions to the
>>               corresponding
>>                      files respectively.
>>
>>                      *ffoplsaa.rtp*
>>
>>                      [ DCE ]
>>                       [ atoms ]
>>                       CLAA opls_967 -0.2270  1
>>                       CAB  opls_966  0.2270  1
>>                       CAC  opls_966  0.2270  2
>>                       CLAD opls_967 -0.2270  2
>>
>>                      [ bonds ]
>>                       CLAA    CAB
>>                       CAB    CAC
>>                       CAC    CLAD
>>
>>                      [ angles ]
>>                       CLAA    CAB    CAC
>>                       CAB    CAC    CLAD
>>
>>                      [ dihedrals ]
>>                       CLAA    CAB    CAC    CLAD
>>
>>                      *ffoplsaa.atp*
>>
>>                       opls_966   14.02700  ; CH2 for DCE
>>                       opls_967   35.45300  ; CL for DCE
>>
>>                      *ffoplsaabon.itp*
>>
>>                      [bondtypes]
>>                      CLAA  CAB     1    0.17870   194137.6   ; CL-CH2
>>        for DCE
>>                      CAB   CAC     1    0.15300   259408.0   ; CH2-CH2
>>        for DCE
>>                      CAC   CLAD    1    0.17870   194137.6   ; CL-CH2
>>        for DCE
>>
>>                      [angletypes]
>>                      CLAA  CAB   CAC       1   108.200    368.192   ;
>>        C-C-CL
>>               for DCE
>>                      CAB   CAC   CLAD      1   108.200    368.192   ;
>>        C-C-CL
>>               for DCE
>>
>>                      [dihedraltypes]
>>                      CLAA   CAB     CAC   CLAD     3     20.76096
>>         -0.4184                 27.011904  0.00000   0.00000   0.00000
>>        ; for DCE
>>
>>
>>                  You shouldn't be using atom names in the [*types]
>>        directives.
>>                What
>>                  you should be using are the interpolated types from
>>               ffoplsaanb.itp,
>>                  thus you have only utilized opls_966 (CAB) and
>>        opls_967 (CLAA).
>>
>>                      *ffoplsaanb.itp*
>>
>>
>>                      opls_966   CAB    6    14.02700    0.227       A
>>              3.98000e-01
>>                       4.76976e-01 ; CH2 of DCE
>>                      opls_967   CLAA   17   35.45300   -0.227       A
>>              3.16000e-01
>>                       0.20920e+01 ; Cl of DCE
>>
>>                      *dce.pdb*
>>
>>                      HETATM    1 CLAA DCE     1       6.300  -2.280
>>    1.360  1.00
>>                      20.00            CL
>>                      HETATM    2  CAB DCE     1       5.060  -3.540
>>    1.500  1.00
>>                      20.00             C
>>                      HETATM    3  CAC DCE     1       4.320  -3.740
>>    0.170  1.00
>>                      20.00             C
>>                      HETATM    4 CLAD DCE     1       3.270  -2.350
>>         -0.210  1.00
>>                      20.00            CL
>>
>>                      After adding all this, when i run grompp i get the
>>        error as
>>                      *fatal error Unknown bond_atomtype CLAA*. can any
>>        one tell me
>>                      why this happens?.
>>
>>
>>                  Have you been sure to #include the correct (modified)
>>        force field
>>                  files?  That is, if you made a local copy and adjusted
>>        them,
>>               these
>>                  won't be the files that pdb2gmx will #include by default.
>>
>>                  -Justin
>>
>>                      Regards
>>                      Vinoth
>>
>>
>>                  --     ========================================
>>
>>                  Justin A. Lemkul
>>                  Ph.D. Candidate
>>                  ICTAS Doctoral Scholar
>>                  MILES-IGERT Trainee
>>                  Department of Biochemistry
>>                  Virginia Tech
>>                  Blacksburg, VA
>>                  jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu>
>>        <http://vt.edu> | (540)
>>
>>               231-9080
>>
>>                  http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>>
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>>           --     ========================================
>>
>>           Justin A. Lemkul
>>           Ph.D. Candidate
>>           ICTAS Doctoral Scholar
>>           MILES-IGERT Trainee
>>           Department of Biochemistry
>>           Virginia Tech
>>           Blacksburg, VA
>>           jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu> | (540)
>>        231-9080
>>           http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>>
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>>
>>    --     ========================================
>>
>>    Justin A. Lemkul
>>    Ph.D. Candidate
>>    ICTAS Doctoral Scholar
>>    MILES-IGERT Trainee
>>    Department of Biochemistry
>>    Virginia Tech
>>    Blacksburg, VA
>>    jalemkul[at]vt.edu <http://vt.edu> | (540) 231-9080
>>    http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>>
>>    ========================================
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> --
> ========================================
>
> Justin A. Lemkul
> Ph.D. Candidate
> ICTAS Doctoral Scholar
> MILES-IGERT Trainee
> Department of Biochemistry
> Virginia Tech
> Blacksburg, VA
> jalemkul[at]vt.edu | (540) 231-9080
> http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>
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