tekle...@ualberta.ca wrote:
Hi Justin,
It does not work. I eliminated the hydrogen atoms and check the entire
.pdb file but could not solve the problem.
the modified PDB file.
REMARK This PDB file is created by CS Chem3D
REMARK
COMPND Tolene.pdb
HETATM 1 CB PHE 0 -1.158 0.001 0.000
CH2
HETATM 2 CG PHE 0 -1.158 -1.336
0.000 C
HETATM 3 CD1 PHE 0 -0.000 -2.004 0.000
CR1
HETATM 4 CD2 PHE 0 1.158 -1.336 0.000
CR1
HETATM 5 CE1 PHE 0 1.158 0.001 0.000
CR1
HETATM 6 CE2 PHE 0 -0.000 0.670 0.000
CR1
HETATM 7 CZ PHE 0 -0.000 2.167 0.000
CR1
END
Opening library file /usr/local/gromacs/share/gromacs/top/ffG43a1.rtp
Opening library file /usr/local/gromacs/share/gromacs/top/aminoacids.dat
Opening library file /usr/local/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 /usr/local/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 /usr/local/gromacs/share/gromacs/top/vdwradii.dat
Entries in vdwradii.dat: 28
Opening library file /usr/local/gromacs/share/gromacs/top/dgsolv.dat
Entries in dgsolv.dat: 7
Opening library file /usr/local/gromacs/share/gromacs/top/electroneg.dat
Entries in electroneg.dat: 71
Opening library file /usr/local/gromacs/share/gromacs/top/elements.dat
Entries in elements.dat: 218
Reading Tolene.pbd.gro...
-------------------------------------------------------
Program pdb2gmx, VERSION 4.0.5
Source code file: futil.c, line: 330
File input/output error:
Tolene.pbd.gro
-------------------------------------------------------
"It's So Lonely When You Don't Even
Any comment on that.
It's a pretty obvious typo; .pbd != .pdb.
-Justin
Rob
Quoting "Justin A. Lemkul" <jalem...@vt.edu>:
tekle...@ualberta.ca wrote:
Dear Justin,
It really help all the feedback you gave me and thank you for that,.
I have one issues as well.
I try to generate the topology file the way you recommend me using
the pdb2gro but failed to get both the topology and gromacs file.
This is my Toluene file in pdb file
REMARK This PDB file is created by CS Chem3D
REMARK
COMPND Tolene.pdb
HETATM 1 CB PHE 0 -1.158 0.001 0.000
C
HETATM 2 CG PHE 0 -1.158 -1.336 0.000
C
HETATM 3 CD1 PHE 0 -0.000 -2.004 0.000
C
HETATM 4 CD2 PHE 0 1.158 -1.336 0.000
C
HETATM 5 CE1 PHE 0 1.158 0.001 0.000
C
HETATM 6 CE2 PHE 0 -0.000 0.670 0.000
C
HETATM 7 CZ PHE 0 -0.000 2.167 0.000
C
HETATM 8 H16 PHE 0 -2.111 0.551 0.000
H
HETATM 9 H17 PHE 0 -2.111 -1.886 0.000
H
HETATM 10 H18 PHE 0 -0.000 -3.104 0.000
H
HETATM 11 H19 PHE 0 2.110 -1.886 0.000
H
HETATM 12 H20 PHE 0 2.110 0.551 0.000
H
HETATM 13 H21 PHE 0 1.049 2.538 0.000
H
HETATM 14 H22 PHE 0 -0.524 2.537 -0.909
H
HETATM 15 H23 PHE 0 -0.525 2.537 0.909
H
END
I run
pdb2gmx -ff G43a1 -f TOL.pdb -o TOL.gro -p TOL.top -missing
but I go the following error.
Opening library file /usr/local/gromacs/share/gromacs/top/electroneg.dat
Entries in electroneg.dat: 71
Opening library file /usr/local/gromacs/share/gromacs/top/elements.dat
Entries in elements.dat: 218
Reading YY.pdb...
Read 'Tolene.pdb', 15 atoms
Opening library file /usr/local/gromacs/share/gromacs/top/xlateat.dat
26 out of 26 lines of xlateat.dat converted succesfully
Analyzing pdb file
There are 1 chains and 0 blocks of water and 1 residues with 15 atoms
chain #res #atoms
1 ' ' 1 15
All occupancy fields zero. This is probably not an X-Ray structure
Opening library file /usr/local/gromacs/share/gromacs/top/ffG43a1.atp
Atomtype 1
I tried many times but could not get the topology file.
Can you comment on this please.
What you've shown isn't an error. It reflects the fact that you don't
even have occupancy values in this .pdb file. You will certainly have
a nomenclature problem, though - your H atoms are not named according
to what the .rtp file expects, so you'll either need to delete the H
atoms and let pdb2gmx rebuild them from the .hdb entries, or use -ignh.
-Justin
Rob
Quoting "Justin A. Lemkul" <jalem...@vt.edu>:
tekle...@ualberta.ca wrote:
Dear Gromacs Users,
I have encountered the following issues while I was running my MD
simulation. Can anybody comment on what the meaning of these notes
are. Is there anything I could do to avoid them.
NOTE 2 [file PAP.top, line unknown]:
The largest charge group contains 12 atoms.
Since atoms only see each other when the centers of geometry of the
charge
groups they belong to are within the cut-off distance, too large
charge
groups can lead to serious cut-off artifacts.
For efficiency and accuracy, charge group should consist of a few
atoms.
For all-atom force fields use: CH3, CH2, CH, NH2, NH, OH, CO2, CO,
etc.
My SOLVENT IS TOLUENE --- the PRODRG gave me a topology file with
only one group charge only.
That's almost certainly wrong. See, for instance, the PHE side
chain in the relevant .rtp entry for a more reasonable charge group
setup. If you're using PRODRG defaults, then the charges are
probably unsatisfactory, as well.
The rationale for the charge group size is summed up here:
http://lists.gromacs.org/pipermail/gmx-users/2008-November/038153.html
NOTE 1 [file nvt.mdp, line unknown]:
The Berendsen thermostat does not generate the correct kinetic energy
distribution. You might want to consider using the V-rescale
thermostat.
See the literature about this one, as well as the numerous list
archive discussions. For initial equilibration, a weak coupling
scheme is probably fine, but you can also use V-rescale. Also of
interest:
http://www.gromacs.org/Documentation/Terminology/Thermostats
NOTE 3 [file aminoacids.dat, line 1]:
The optimal PME mesh load for parallel simulations is below 0.5
and for highly parallel simulations between 0.25 and 0.33,
for higher performance, increase the cut-off and the PME grid spacing
This all depends on the size of your system, how much of the work is
distributed between the real-space Coulombic interaction and PME.
In addition to the above notes I have also some questions about
the NVT and NPT simulation.
1)I am using toluene as a solvent to simulate my polymer, do I need
to use the compressibility of toluene which is 9.2e-5 or the
default value 4.5e-5 1/bar.
Well, 4.5e-5 corresponds to water, which you aren't using...
For NVT, this won't matter since the box is fixed, but for NPT, the
compressibility will affect the response of your system to
pressure. The differences may be minimal, but if you know the right
value, why accept a wrong one?
2)What about the dielectric constant (the dielectric constant for
toluene is 2-2.4), but the default value is 80 ( I assume this is
for water- am I right).
Yes, the default again assumes water as the solvent.
3)Is always rvdw = 1.4 nm for GROMOS96. As a result I have to
increase my box size of the solute at the beginning to a min of
2*1.4 =2.8 ( min image convection). Is this the right way to do!
At an absolute minimum. Keep in mind that the box vectors will
fluctuate under NPT, so if the box decreases even a little bit below
2.8, you will be violating the minimum image convention.
4)I run an NVT simulation to equilibrate my system for 100 ps.
When I checked my simulation at the end (successfully completed) I
noticed that the shape of my simulation box looks CIRCULAR! some
how the rectangular shape looks distorted. What does this tell! Do
you guys think something is wrong in my simulation.
This could be some visualization artifact, or the components of your
system have condensed within the box. Without actually seeing it,
it's hard to tell. If you post an image online (Photobucket, etc)
then we might get a better sense of what's going on.
5)I included the polar and aromatic hydrogens in my simulation (
ffG43a1.itp - GROMOS96.1 in PRODRG). Does these hydrogen influence
my result as the force field is a united atom force field. Or How
can I get rid of them if I want. With or without the aromatic
hydrogen gave good results ( besides lower computational cost).
Does Gromos96 model correctly aromatic-Aromatic interaction.
Well, "correct" is a relative term for all force fields, but you
need to follow the prescribed setup of the force field itself,
otherwise you can throw it all away. If you lump the hydrogens into
the ring carbons and have an uncharged ring, the result will be
different than if you have the hydrogens there with a small charge
on each C and H. Again, refer to the force field .rtp file for
examples. You can also create a better toluene topology by renaming
the residue in your coordinate file PHE and trick pdb2gmx:
pdb2gmx -f toluene.pdb -missing
Then change the mass of the CH2 group (which pdb2gmx thinks is a CB
for PHE) to reflect a CH3 group. Make an .itp file out of the
resulting .top by removing the unnecessary #includes, [system], and
[molecule] directives. Then you don't have to worry about messing
with PRODRG. I should note, as well, that this is about the only
appropriate use of -missing I can think of at the moment (just for
clarity in the archives; I usually warn against using -missing).
-Justin
--
========================================
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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--
========================================
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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Please search the archive at http://www.gromacs.org/search before
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interface or send it to gmx-users-requ...@gromacs.org.
Can't post? Read http://www.gromacs.org/mailing_lists/users.php
--
========================================
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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