[gmx-users] Need to search parameters.

[Sailesh Bataju]

Hi,

I need to search parameters like bond length, bond angle, atomic charge,
dihedral angle, improper dihedral angle and Lennard Jones potential
parameters like C6 and C12 of isobutane molecule. I've searched those
parameters in ffbonded.itp and ffnonbonded.itp files inside gromos54a7
forcefield. Also i've downloaded isobutane.itp for opls forcefield file
from virtualchemistry.org site but I've no idea how do I extract those
informations from such files.

Thank you for your guidance.

Isobutane.itp contains
; This include topology was generated for the paper below:
; Carl Caleman, Paul J. van Maaren, Minyan Hong, Jochen S. Hub,
; Luciano T. Costa and David van der Spoel
; Force Field Benchmark of Organic Liquids: Density,
; Enthalpy of Vaporization, Heat Capacities, Surface Tension,
; Isothermal Compressibility, Volumetric Expansion Coefficient,
; and Dielectric Constant
; J. Chem. Theor. Comput. 8 (2012) 61-74
; http://dx.doi.org/10.1021/ct200731v
; REFERENCE Caleman2012a
[ moleculetype ]
 ; Name            nrexcl
 isobutane  3

 [ atoms ]
 ;   nr       type  resnr residue  atom   cgnr     charge       mass  typeB
   chargeB      massB
          1  opls_135         1       LIG         C         1     -0.18
 12.011
          2  opls_140         1       LIG         H         2      0.06
1.008
          3  opls_140         1       LIG         H         3      0.06
1.008
          4  opls_140         1       LIG         H         4      0.06
1.008
          5  opls_137         1       LIG         C         5     -0.06
 12.011
          6  opls_140         1       LIG         H         6      0.06
1.008
          7  opls_135         1       LIG         C         7     -0.18
 12.011
          8  opls_140         1       LIG         H         8      0.06
1.008
          9  opls_140         1       LIG         H         9      0.06
1.008
         10  opls_140         1       LIG         H        10      0.06
1.008
         11  opls_135         1       LIG         C        11     -0.18
 12.011
         12  opls_140         1       LIG         H        12      0.06
1.008
         13  opls_140         1       LIG         H        13      0.06
1.008
         14  opls_140         1       LIG         H        14      0.06
1.008

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

 [ pairs ]
 ;  ai    aj funct            c0            c1            c2            c3
     1     8     1
     1     9     1
     1    10     1
     1    12     1
     1    13     1
     1    14     1
     2     6     1
     2     7     1
     2    11     1
     3     6     1
     3     7     1
     3    11     1
     4     6     1
     4     7     1
     4    11     1
     6     8     1
     6     9     1
     6    10     1
     6    12     1
     6    13     1
     6    14     1
     7    12     1
     7    13     1
     7    14     1
     8    11     1
     9    11     1
    10    11     1

 [ angles ]
 ;  ai    aj    ak funct            c0            c1            c2
   c3
     2     1     3     1
     2     1     4     1
     2     1     5     1
     3     1     4     1
     3     1     5     1
     4     1     5     1
     1     5     6     1
     1     5     7     1
     1     5    11     1
     6     5     7     1
     6     5    11     1
     7     5    11     1
     5     7     8     1
     5     7     9     1
     5     7    10     1
     8     7     9     1
     8     7    10     1
     9     7    10     1
     5    11    12     1
     5    11    13     1
     5    11    14     1
    12    11    13     1
    12    11    14     1
    13    11    14     1

 [ dihedrals ]
 ;  ai    aj    ak    al funct            c0            c1            c2
         c3            c4            c5
     2     1     5     6     3
     2     1     5     7     3
     2     1     5    11     3
     3     1     5     6     3
     3     1     5     7     3
     3     1     5    11     3
     4     1     5     6     3
     4     1     5     7     3
     4     1     5    11     3
     1     5     7     8     3
     1     5     7     9     3
     1     5     7    10     3
     6     5     7     8     3
     6     5     7     9     3
     6     5     7    10     3
    11     5     7     8     3
    11     5     7     9     3
    11     5     7    10     3
     1     5    11    12     3
     1     5    11    13     3
     1     5    11    14     3
     6     5    11    12     3
     6     5    11    13     3
     6     5    11    14     3
     7     5    11    12     3
     7     5    11    13     3
     7     5    11    14     3



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