[gmx-users] Generating topology with pdb2gmx

Moeed lecielll at googlemail.com
Sun May 9 00:36:20 CEST 2010


Dear Justin,

1- Unfortunately, I am having difficulty running the simple program pdb2gmx
with pdb file you sent me for Hexane.. I have in working directory pdb file
and rtp files:
Hexane-PRODRG.pdb  rtp.pdb

pdb2gmx -f Hexane-PRODRG.pdb -o Hexane.gro -p Hexane.top >& output.pdb2gmx

output.pdb2gmx says:

Opening library file /chem_soft/gromacs/share/gromacs/top/FF.dat

2-can you please tell me why I need rtp file? previously I just created pdb
file and used x2top an dI had no rtp file...

Thank you for your help.

******************************************************************
Hexane-PRODRG.pdb:


CRYST1    0.000    0.000    0.000  90.00  90.00  90.00 P 1           1
ATOM      1  C1      HEX 1       8.330   1.510  -0.010  0.00  0.00
C
ATOM      2  H11     HEX 1       9.281   1.200  -0.024  0.00  0.00
H
ATOM      3  H12     HEX 1       8.154   2.080  -0.813  0.00  0.00
H
ATOM      4  H13     HEX 1       8.166   2.044   0.820  0.00  0.00
H
ATOM      5  C2      HEX 1       7.400   0.300  -0.030  0.00  0.00
C
ATOM      6  H21     HEX 1       7.584  -0.267   0.773  0.00  0.00
H
ATOM      7  H22     HEX 1       7.573  -0.231  -0.860  0.00  0.00
H
ATOM      8  C3      HEX 1       5.940   0.730  -0.010  0.00  0.00
C
ATOM      9  H31     HEX 1       5.754   1.291  -0.816  0.00  0.00
H
ATOM     10  H32     HEX 1       5.769   1.266   0.817  0.00  0.00
H
ATOM     11  C4      HEX 1       5.010  -0.480  -0.020  0.00  0.00
C
ATOM     12  H41     HEX 1       5.192  -1.038   0.790  0.00  0.00
H
ATOM     13  H42     HEX 1       5.186  -1.020  -0.843  0.00  0.00
H
ATOM     14  C5      HEX 1       3.540  -0.050  -0.010  0.00  0.00
C
ATOM     15  H51     HEX 1       3.357   0.507  -0.820  0.00  0.00
H
ATOM     16  H52     HEX 1       3.363   0.489   0.813  0.00  0.00
H
ATOM     17  C6      HEX 1       2.610  -1.270  -0.020  0.00  0.00
C
ATOM     18  H61     HEX 1       1.658  -0.964  -0.013  0.00  0.00
H
ATOM     19  H62     HEX 1       2.780  -1.812  -0.843  0.00  0.00
H
ATOM     20  H63     HEX 1       2.785  -1.830   0.790  0.00  0.00
H
END

*******************************rtp.pdb :

[ HEX ]
 [ atoms ]
   C1   opls_157    -0.180      1
   H11  opls_140     0.060      1
   H12  opls_140     0.060      1
   H13  opls_140     0.060      1
   C2   opls_158    -0.120      2
   H21  opls_140     0.060      2
   H22  opls_140     0.060      2
   C3   opls_158    -0.120      3
   H31  opls_140     0.060      3
   H32  opls_140     0.060      3
   C4   opls_158    -0.120      4
   H41  opls_140     0.060      4
   H42  opls_140     0.060      4
   C5   opls_158    -0.120      5
   H51  opls_140     0.060      5
   H52  opls_140     0.060      5
   C6   opls_157    -0.180      6
   H61  opls_140     0.060      6
   H62  opls_140     0.060      6
   H63  opls_140     0.060      6
 [ bonds ]
   C1  H11
   C1  H12
   C1  H13
   C1  C2
   C2  H21
   C2  H22
   C2  C3
   C3  H31
   C3  H32
   C3  C4
   C4  H41
   C4  H42
   C4  C5
   C5  H51
   C5  H52
   C5  C6
   C6  H61
   C6  H62
   C6  H63



****************************************************************************************Also
I have tried x2top comamnd: x2top -f Hexane-PRODRG.pdb -o Hexane.top -alldih
-ff oplsaa -name HEX
as you suggested I am using -alldih flag to generate all dihedrals

Option     Filename  Type         Description
------------------------------------------------------------
  -f Hexane-PRODRG.pdb  Input        Structure file: gro g96 pdb tpr tpb tpa
  -o     Hexane.top  Output, Opt! Topology file
  -r        out.rtp  Output, Opt. Residue Type file used by pdb2gmx

Option       Type   Value   Description
------------------------------------------------------
-[no]h       bool   no      Print help info and quit
-nice        int    0       Set the nicelevel
-ff          string oplsaa  Force field for your simulation. Type "select"
                            for interactive selcection.
-[no]v       bool   no      Generate verbose output in the top file.
-nexcl       int    3       Number of exclusions
-[no]H14     bool   yes     Use 3rd neighbour interactions for hydrogen
atoms
-[no]alldih  bool   yes     Generate all proper dihedrals
-[no]remdih  bool   no      Remove dihedrals on the same bond as an improper
-[no]pairs   bool   yes     Output 1-4 interactions (pairs) in topology file
-name        string HEX     Name of your molecule
-[no]pbc     bool   yes     Use periodic boundary conditions.
-[no]pdbq    bool   no      Use the B-factor supplied in a pdb file for the
                            atomic charges
-[no]param   bool   yes     Print parameters in the output
-[no]round   bool   yes     Round off measured values
-kb          real   400000  Bonded force constant (kJ/mol/nm^2)
-kt          real   400     Angle force constant (kJ/mol/rad^2)
-kp          real   5       Dihedral angle force constant (kJ/mol/rad^2)

Opening library file /chem_soft/gromacs/share/gromacs/top/aminoacids.dat
WARNING: masses will be determined based on residue and atom names,
         this can deviate from the real mass of the atom type
Opening library file /chem_soft/gromacs/share/gromacs/top/atommass.dat
Entries in atommass.dat: 178
WARNING: vdwradii will be determined based on residue and atom names,
         this can deviate from the real mass of the atom type
Opening library file /chem_soft/gromacs/share/gromacs/top/vdwradii.dat
Entries in vdwradii.dat: 28
Opening library file /chem_soft/gromacs/share/gromacs/top/dgsolv.dat
Entries in dgsolv.dat: 7
Opening library file /chem_soft/gromacs/share/gromacs/top/electroneg.dat
Entries in electroneg.dat: 71
Opening library file /chem_soft/gromacs/share/gromacs/top/elements.dat
Entries in elements.dat: 218
Looking whether force field files exist
Opening library file /chem_soft/gromacs/share/gromacs/top/ffoplsaa.rtp
Opening library file /chem_soft/gromacs/share/gromacs/top/ffoplsaa.n2t
Opening library file /chem_soft/gromacs/share/gromacs/top/ffoplsaa.n2t
There are 23 name to type translations
Generating bonds from distances...
atom 0
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