[gmx-users] Re: Reg: Gromacs binary liquid-liquid simulation

vinothkumar mohanakrishnan kmvinoth at gmail.com
Mon Sep 13 14:19:08 CEST 2010


hi i have 20 coordinates in the .gro file from PRODRG server where as i have
only 6 atom coordidates in the .top file this file also i got from PRODRG.
below i am giving both my .top file as well as .gro file for hexane. do i
manually edit the .top file from PRODRG to match the coordinates, if so
how?.my worry again is when i give this command

genbox -cp hexane_box.gro -ci hexane_box.gro -p hexane.top -o
hexane_multi.gro -nmol 100 -seed 1997

the .top file doesn't get updated with more number (say 101) of hexane
molecules in the molecules section.kindly advice me on this point.

hexane.top

#include "ffG43a1.itp"

[ moleculetype ]
; Name nrexcl
hexane      3

[ atoms ]
;   nr      type  resnr resid  atom  cgnr   charge     mass
     1       CH3     1  DRG     CAA     1   -0.018  15.0350
     2       CH2     1  DRG     CAB     1    0.011  14.0270
     3       CH2     1  DRG     CAC     1    0.008  14.0270
     4       CH2     1  DRG     CAD     1    0.009  14.0270
     5       CH2     1  DRG     CAE     1    0.009  14.0270
     6       CH3     1  DRG     CAF     1   -0.019  15.0350

[ bonds ]
; ai  aj  fu    c0, c1, ...
   2   1   2    0.153   7150000.0    0.153   7150000.0 ;   CAB  CAA
   2   3   2    0.153   7150000.0    0.153   7150000.0 ;   CAB  CAC
   3   4   2    0.153   7150000.0    0.153   7150000.0 ;   CAC  CAD
   4   5   2    0.153   7150000.0    0.153   7150000.0 ;   CAD  CAE
   5   6   2    0.153   7150000.0    0.153   7150000.0 ;   CAE  CAF

[ pairs ]
; ai  aj  fu    c0, c1, ...
   1   4   1                                           ;   CAA  CAD
   2   5   1                                           ;   CAB  CAE
   3   6   1                                           ;   CAC  CAF

[ angles ]
; ai  aj  ak  fu    c0, c1, ...
   1   2   3   2    109.5       520.0    109.5       520.0 ;   CAA  CAB
CAC
   2   3   4   2    109.5       520.0    109.5       520.0 ;   CAB  CAC
CAD
   3   4   5   2    109.5       520.0    109.5       520.0 ;   CAC  CAD
CAE
   4   5   6   2    109.5       520.0    109.5       520.0 ;   CAD  CAE
CAF

[ dihedrals ]
; ai  aj  ak  al  fu    c0, c1, m, ...
   4   3   2   1   1      0.0    5.9 3      0.0    5.9 3 ; dih   CAD  CAC
CAB  CAA
   5   4   3   2   1      0.0    5.9 3      0.0    5.9 3 ; dih   CAE  CAD
CAC  CAB
   6   5   4   3   1      0.0    5.9 3      0.0    5.9 3 ; dih   CAF  CAE
CAD  CAC

; Include SPC water topology
#include "spc.itp"

[ system ]
hexane in water

[ molecules ]
;molecule name number
hexane         101
SOL              1764

hexane.gro
PRODRG COORDS
   20
    1DRG  CAA      1   0.684  -0.063   1.332
    1DRG  HAA      2   0.684   0.013   1.254
    1DRG  HAB      3   0.583  -0.075   1.371
    1DRG  HAC      4   0.724  -0.158   1.295
    1DRG  CAB      5   0.778  -0.021   1.445
    1DRG  HAD      6   0.776  -0.098   1.522
    1DRG  HAE      7   0.744   0.077   1.479
    1DRG  CAC      8   0.923  -0.003   1.396
    1DRG  HAF      9   0.950  -0.087   1.332
    1DRG  HAG     10   0.985   0.007   1.485
    1DRG  CAD     11   0.940   0.127   1.316
    1DRG  HAH     12   0.913   0.211   1.380
    1DRG  HAI     13   0.878   0.117   1.227
    1DRG  CAE     14   1.085   0.145   1.267
    1DRG  HAJ     15   1.087   0.222   1.190
    1DRG  HAK     16   1.118   0.047   1.232
    1DRG  CAF     17   1.179   0.186   1.380
    1DRG  HAM     18   1.149   0.284   1.418
    1DRG  HAN     19   1.281   0.191   1.342
    1DRG  HAL     20   1.168   0.108   1.456
   0.84818   0.84818   0.84818

Regards
Vinoth

On Mon, Sep 13, 2010 at 4:26 PM, Justin A. Lemkul <jalemkul at vt.edu> wrote:

>
>
> vinothkumar mohanakrishnan wrote:
>
>> i want to do MD for hexane-water system. I got hexane.gro and hexane..itp
>> from PRODRG 2.5 Beta server with that i made the hexane.top file. below is
>> the serious of commands i executed in gromacs, i am adding 200 hexane
>> molecules an 1115 water molecules. after the first genbox i checked my
>> topolgy file wheather the no .of hexane molecules got updated r increased to
>> 200 but it doesn't and remains as 1 and then i maually changed it to 200 in
>> the molecules section. i dont know where
>>
>
> Per your genbox command below, if you have one hexane (in hexane_box.gro)
> and you add 200 (with -nmol), you should then have 201 hexane molecules in
> the system.
>
>
>  iam going wrong and i always get the error message as " number of
>> coordinates in coordinate file (hexane_solv.gro, 7365) does not match
>> topology (hexane.top, 4545) " while running grompp for energy minimisation.
>> i read the error gromacs (website) documentation and found that the
>> hexane.top r hexane.gro file is not getting updated, but iam helpless. any
>> help is highly appreciated. below is my topology file as well.
>>
>>
> Follow my previous advice and see if you can trace back where the error
> came from.  Count the molecules in your .gro file, i.e.:
>
> grep OW hexane_solv.gro | wc -l
>
> will give you the number of water molecules.  Do something analogous for
> hexane.  You're off by 2820 atoms, which is in the ballpark of 940 waters,
> so something has broken down pretty badly somewhere.
>
> -Justin
>
>
>  ; The force field files to be included
>> #include "ffG43a1.itp"
>>
>> ; Include hexane topology
>> #include "hexane.itp"
>>
>> ; Include SPC water topology
>> #include "spc.itp"
>>
>> [ system ]
>> hexane in Water
>>
>> [ molecules ]
>> ;molecule name number
>> hexane         200
>> SOL              1115
>> *
>> Commands*
>>
>>  editconf -f hexane.gro -o hexane_box.gro -c -bt triclinic -box 8.31 3.01
>> 3.01
>>
>> genbox -cp hexane_box.gro -ci hexane_box.gro -p hexane.top -o
>> hexane_multi.gro -nmol 200 -seed 1997
>>
>> genbox -cp hexane_multi.gro -cs spc216.gro -p hexane.top -o
>> hexane_solv.gro
>>
>> grompp -f em.mdp -c hexane_solv.gro -p hexane.top -o hexane_em.tpr
>>
>> 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 | (540) 231-9080
> http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>
> ========================================
>
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