[gmx-users] setting up forcefield

saicheong chung saicheong.chung at jp.sony.com
Fri Dec 21 03:51:21 CET 2001


Dear all,

I tried to run a simulation of the polymer with 
SHAKE-fixed bond/angles.  Taking into account
only the dihedrals, charge and LJ forces.  I
want to use a non-default forcefield taking from
a publication.  

I somehow managed to take the trouble of mimicing the
ffgmx forcefield and created the corresponding files
in the "top" directory.  And pdb2gmx and grompp are
able to generate the tpr file.  However, there must
be something wrong that my molecule is alway exploding
and got the "shake error".   I am at lost where to
look now.  Would you please give me some tips?

attached are the forcefield files and the test. 

thanks
sai
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   CF  12.01100 ;     flurinated carbon (C-F)
   SO  32.066   ;     sulphite S  (SO3-)
   OS  15.99940 ;     oxygen in sulphite (SO3-)
   FC  18.99840 ;     fluorine  bonded to carbon (C-F)
   O1  15.99940 ;     ether oxygen in nafion side chain
   CH3 15.0350  ;     CH3
   OW  15.99940 ;     WATER OXYGEN
   HW   1.00800 ;     WATER HYDROGEN
   KP  39.0983  ;     potassium ion

   
-------------- next part --------------
; Residual files for the simulation of nafion related materials

[ bondedtypes ]
; bonds  angles  dihedrals  impropers
     1       1          1          2

[ NAF ]
[ atoms ]
    CH3     CH3    0.000     0
     C1     CF     0.329     0
    F11     FC    -0.166     0
    F12     FC    -0.166     0
     C2     CF     0.329     0
    F21     FC    -0.166     0
    F22     FC    -0.166     0
     O1     O1    -0.260     0
     C3     CF     0.322     0
    F31     FC    -0.166     0
    F32     FC    -0.166     0
     C4     CF     0.322     0
    F41     FC    -0.328     0
    F42     FC    -0.328     0
     S1     SO     1.412     0
    O12     OS    -0.632     0
    O13     OS    -0.632     0
    O11     OS    -0.632     0
    K       KP    +1.000     1
[ bonds ]
	CH3     C1
	C1	F11
	C1	F12
	C1	C2
	C2	F21
	C2	F22
	C2	O1
	O1	C3
	C3	F31
	C3	F32
	C3	C4
	C4	F41
	C4	F42
	C4	S1
	S1	O12
	S1	O13
	S1	O11

[ dihedrals ]
;  ai    aj    ak    al funct            c0            c1            
   CH3 C1 C2 O1
   C1  C2 O1 C3
   C2  O1 C3 C4
   O1  C3 C4 S1
   C3  C4 S1 O


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[ atomtypes ]
;name        mass      charge   ptype            c6           c12
   CF    12.01100       0.000       A   2.79435e-03   4.90354e-06  
   SO    32.066         0.000       A   8.37856e-03   1.67702e-05  
   OS    15.99940       0.000       A   3.27154e-03   3.19607e-06  
   FC    18.99840       0.000       A   1.06291e-03   9.30631e-07  
   O1    15.99940       0.000       A   2.38335e-03   1.99534e-06  
   CH3   15.03500       0.000       A   0.88765E-02   0.26150E-04
#ifdef HEAVY_H
   OW     9.95140       0.000       A   0.26171E-02   0.26331E-05
#else
   OW    15.99940       0.000       A   0.26171E-02   0.26331E-05
#endif
#ifdef HEAVY_H
   HW     4.03200       0.000       A   0.00000E+00   0.00000E+00
#else
   HW     1.00800       0.000       A   0.00000E+00   0.00000E+00
#endif
   KP     39.0983        0.000       A   0.88765E-02   0.26150E-04


-------------- next part --------------
;
;	File 'topol.top' was generated
;	By user: taro (39586)
;	On host: SGI-ryuichiro
;	At date: Sat Apr 21 20:28:39 2001
;
;	This is your topology file
;	"In a Deep Deep Well" (Nick Cave)
;
; Include forcefield parameters
#include "ffnafi.itp"

[ moleculetype ]
; Name            nrexcl
Protein             3

[ atoms ]
;   nr   type  resnr residue  atom   cgnr     charge       mass  typeB    chargeB      massB
     1    CH3      1    NAF    CH3      1          0     15.035   ; qtot 0
     2     CF      1    NAF     C1      1      0.329     12.011   ; qtot 0.329
     3     FC      1    NAF    F11      1     -0.166    18.9984   ; qtot 0.163
     4     FC      1    NAF    F12      1     -0.166    18.9984   ; qtot -0.00299999
     5     CF      1    NAF     C2      1      0.329     12.011   ; qtot 0.326
     6     FC      1    NAF    F21      1     -0.166    18.9984   ; qtot 0.16
     7     FC      1    NAF    F22      1     -0.166    18.9984   ; qtot -0.00599998
     8     O1      1    NAF     O1      1      -0.26    15.9994   ; qtot -0.266
     9     CF      1    NAF     C3      1      0.322     12.011   ; qtot 0.056
    10     FC      1    NAF    F31      1     -0.166    18.9984   ; qtot -0.11
    11     FC      1    NAF    F32      1     -0.166    18.9984   ; qtot -0.276
    12     CF      1    NAF     C4      1      0.322     12.011   ; qtot 0.046
    13     FC      1    NAF    F41      1     -0.328    18.9984   ; qtot -0.282
    14     FC      1    NAF    F42      1     -0.328    18.9984   ; qtot -0.61
    15     SO      1    NAF     S1      1      1.412     32.066   ; qtot 0.802
    16     OS      1    NAF    O12      1     -0.632    15.9994   ; qtot 0.17
    17     OS      1    NAF    O13      1     -0.632    15.9994   ; qtot -0.462
    18     OS      1    NAF    O11      1     -0.632    15.9994   ; qtot -1.094
    19     KP      1    NAF      K      2          1    39.0983   ; qtot -0.0940001

[ bonds ]
;  ai    aj funct            c0            c1            c2            c3
    1     2     1 
    2     3     1 
    2     4     1 
    2     5     1 
    5     6     1 
    5     7     1 
    5     8     1 
    8     9     1 
    9    10     1 
    9    11     1 
    9    12     1 
   12    13     1 
   12    14     1 
   12    15     1 
   15    16     1 
   15    17     1 
   15    18     1 

[ dihedrals ]
;  ai    aj    ak    al funct            c0            c1            c2            c3            c4            c5
    1     2     5     8     1 
    2     5     8     9     1 
    5     8     9    12     1 
    8     9    12    15     1 
    9    12    15    16     1 

; Include Position restraint file
#ifdef POSRES
#include "posre.itp"
#endif

; Include water topology
#ifdef FLEX_SPC
#include "flexspc.itp"
#else
#include "spc.itp"
#endif

#ifdef POSRES_WATER
; Position restraint for each water oxygen
[ position_restraints ]
;  i funct       fcx        fcy        fcz
   1    1       1000       1000       1000
#endif

[ system ]
; Name
Protein in water

[ molecules ]
; Compound        #mols
Protein             1
SOL               121
-------------- next part --------------
GRowing Old MAkes el Chrono Sweat
   19
    1NAF    CH3    1   0.906   0.529   0.720
    1NAF     C1    2   0.894   0.667   0.641
    1NAF    F11    3   0.822   0.648   0.525
    1NAF    F12    4   1.018   0.713   0.608
    1NAF     C2    5   0.814   0.774   0.730
    1NAF    F21    6   0.887   0.804   0.842
    1NAF    F22    7   0.694   0.721   0.769
    1NAF     O1    8   0.789   0.887   0.656
    1NAF     C3    9   0.753   0.991   0.740
    1NAF    F31   10   0.665   0.947   0.836
    1NAF    F32   11   0.866   1.038   0.802
    1NAF     C4   12   0.685   1.108   0.655
    1NAF    F41   13   0.576   1.054   0.591
    1NAF    F42   14   0.775   1.147   0.559
    1NAF     S1   15   0.636   1.248   0.757
    1NAF    O12   16   0.637   1.368   0.668
    1NAF    O13   17   0.746   1.246   0.858
    1NAF    O11   18   0.502   1.208   0.808
    1NAF      K   19   0.741   1.485   0.971
   1.51600   1.95600   1.44600


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