[gmx-users] Normal Mode

2015-11-08 Thread Dan Sponseller
Hello everyone.

I am doing a Normal Mode analysis on a small polymer. Just 17 atoms in vacuo. 
It is well minimized. Norm and Max Force < 1e-4. I am doing the analysis on the 
full precision configuration using the -t option.

I am getting 6 eigen frequencies and 5 eigenvalues near zero which is of course 
good. 

However, I am getting 16 eigenfrequencies from 5000 to 21,000 cm-1 with 
enormous eigenvalues. This does not appear correct. Any insights as to why 
gromacs is producing these would be appreciated.


Dan Sponseller
PhD candidate
George Mason University.
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[gmx-users] Normal Mode Analysis

2015-10-14 Thread Dan Sponseller
Hello.

I am trying to do a Normal Mode Analysis of a polymer in water. I am running my 
minimization right now with -DFLEXIBLE defined.

How do I exclude the water from the analysis. I only want the analysis done on 
the polymer.

Dan Sponseller
PhD student, George Mason University
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Re: [gmx-users] editconf -density

2015-08-09 Thread Dan Sponseller
You do not state your original density. But lets say you need to reduce volume 
3% to get your correct density. Use:
ediftconf -f solv_large.gro -o solv_large_scaled.gro -scale 1 1 0.97

Just do a quick side calculation for what you need and substitute in for 0.97.

Dan


 On Aug 9, 2015, at 4:18 AM, James Lord jjamesgreen...@gmail.com wrote:
 
 Hi all,
 I have  a solvent filled in a box of dimensions 12 12 12 (solv_large.gro).
 I want to adjust the density of system to 824 kg/m3. But I want editconf to
 just change the volume only by changing the z direction ? is that possible?
 I did
 ediftconf -f solv_large.gro -o solv_large_scaled.gro -density 824
 
 But it changes the x,y,z to adjust the density. Is it possible to ask
 editconf to do this only by changing for example z?
 Cheers
 James
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[gmx-users] Help me with energy groups please.

2015-06-20 Thread Dan Sponseller
For my main MD experiment, I run just the energy group System. This is fine. 
Then I take one configuration and run a minimization. For the minimization, I 
have two energy groups: peg2000 (my polymer), and Water so that I can inspect 
interaction energies.

Here is the output from gmx energy:

Energy  Average   Err.Est.   RMSD  Tot-Drift
---
Morse   13.8929 1192.2316   -69.4839  (kJ/mol)
G96Angle347.715 62127.946   -413.973  (kJ/mol)
Proper Dih. 128.924   0.551.13049 -3.826  (kJ/mol)
LJ-14   71.4762  24.16065   -13.8959  (kJ/mol)
Coulomb-14  988.758   0.12   0.239868   0.836523  (kJ/mol)
LJ (SR)  3263212.9 5.9749   -20.3545  (kJ/mol)
Coulomb (SR) -1.85621e+06   0.360.80798   -2.48026  (kJ/mol)
Coul. recip.2094.03  0.015  0.0317153  0.0976681  (kJ/mol)
LJ recip.  -30437.1 0.0032 0.00707587 -0.0217548  (kJ/mol)
Potential-1.55669e+06 78191.241   -523.261  (kJ/mol)
Pressure -2.80437e+345.7e+27 1.27529e+28 3.80388e+28  (bar)
#Surf*SurfTen-1.35113e+331.8e+29 3.66158e+29 1.18298e+30  (bar 
nm)
Coul-SR:peg2000-peg2000  -1.85621e+06   0.360.80798   -2.48026  (kJ/mol)
LJ-SR:peg2000-peg20003263212.9 5.9749   -20.3545  (kJ/mol)
Coul-14:peg2000-peg2000 988.758   0.12   0.239868   0.836523  (kJ/mol)
LJ-14:peg2000-peg2000   71.4762  24.16065   -13.8959  (kJ/mol)
Coul-SR:peg2000-Water 0  0  0  0  (kJ/mol)
LJ-SR:peg2000-Water   0  0  0  0  (kJ/mol)
Coul-14:peg2000-Water 0  0  0  0  (kJ/mol)
LJ-14:peg2000-Water   0  0  0  0  (kJ/mol)
Coul-SR:Water-Water   0  0  0  0  (kJ/mol)
LJ-SR:Water-Water 0  0  0  0  (kJ/mol)
Coul-14:Water-Water   0  0  0  0  (kJ/mol)
LJ-14:Water-Water 0  0  0  0  (kJ/mol)



ddd
It appears I have no interaction energy between my polymer and the water and 
there is no interaction energy intra-Water. This makes no sense! I am using the 
standard spce water witch does have partial charges and my polymer has partial 
charges. There should be coulomb interaction and there should always be LJ 
interaction.

Help me figure this out please. Attached is my mdp file.

Dan Sponseller


** Run Control **
integrator   = steep
nsteps   = 1
comm-mode= Linear
nstcomm  = 100

** Energy Minimization
emtol= 0.001
emstep   = 0.01

** Output Control **
nstxout  = 0
nstvout  = 0
nstfout  = 0
nstlog   = 0
nstcalcenergy= 1
nstenergy= 1
energygrps   = peg2000 Water

** Neighbor Searching **
cutoff-scheme= Verlet
nstlist  = 20
ns_type  = grid
pbc  = xyz
periodic-molecules   = no
verlet-buffer-tolerance  = 0.001

** Electrostatics **
coulombtype  = PME
coulomb-modifier = Potential-shift-Verlet
rcoulomb = 1.5

** VdW **
vdwtype  = PME
vdw-modifier = Potential-shift-Verlet
rvdw = 1.5

** Ewald **
fourierspacing   = 0.15
pme-order= 6
ewald-rtol   = 1e-5

** Temperature Coupling **
tcoupl   = no
;tcoupl   = v-rescale
nsttcouple   = -1
tc-grps  = System
tau-t= 1.0
ref-t= 300

** Pressure Coupling **
pcoupl   = no
;pcoupl   = Parrinello-Rahman
;pcoupl   = Berendsen
pcoupltype   = isotropic
nstpcouple   = -1
tau-p= 2.0
compressibility  = 4.5e-5
ref-p= 1
refcoord-scaling = all

** Velocity Generation **
gen-vel  = no
gen-temp = 300
gen-seed = 4242

** Bonds **
constraints  = none
morse= yes

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Re: [gmx-users] all in one pc for MD simulation calculations

2015-04-16 Thread Dan Sponseller
Hello.

You do not provide enough detail for any type of answer. For example. I have 
run a small molecule (100 atoms) on my laptop and finished in an hour. I am 
currently running 7 atoms on a computing cluster with 128 CPUs and it will 
take a week or two.

Dan
George Mason University




 On Apr 16, 2015, at 10:49 AM, Atila Petrosian atila.petros...@gmail.com 
 wrote:
 
 Dear gromacs users
 
 
 
 I have a question about computer which is needed for MD simulation by
 gromacs.
 
 
 
 Is an all in one pc appropriate for MD simulation?
 
 
 
 Any help will highly appreciated.
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Re: [gmx-users] Build-Gromacs installation error

2015-02-05 Thread Dan Sponseller
You might not have MPI installed on your computer (or MPICH). However, sounds 
like you are installing this on a personal computer. You should turn off MPI as 
GROMACS’ internal thread MPI is excellent. You only need to turn on MPI if you 
are installing this on a cluster where multiple CPUs are used on separated PCs.

If you really need external MPI, the wrapper compiler is usually called 
‘mpicc’. So set all the cmake variables to this.

Dan
 
 On Feb 6, 2015, at 1:01 AM, rahul dhakne rahuldhakn...@gmail.com wrote:
 
 Hello Everyone,
 
 I am trying to install Gromacs on my computer. But after I run *cmake ..*
 command it display error
 
 -- Enabling native GPU acceleration
 -- Could NOT find MPI_C (missing:  MPI_C_LIBRARIES MPI_C_INCLUDE_PATH)
 -- Could NOT find MPI_CXX (missing:  MPI_CXX_LIBRARIES
 MPI_CXX_INCLUDE_PATH)
 CMake Error at cmake/gmxManageMPI.cmake:150 (message):
  MPI support requested, but no MPI compiler found.  Either set the
  C-compiler (CMAKE_C_COMPILER) to the MPI compiler (often called mpicc), or
  set the variables reported missing for MPI_C above.
 Call Stack (most recent call first):
  CMakeLists.txt:464 (include)
 
 
 -- Configuring incomplete, errors occurred!
 See also
 /home/rose/Software/Gromacs/gromacs-5.0.4/build-gromacs/CMakeFiles/CMakeOutput.log.
 See also
 /home/rose/Software/Gromacs/gromacs-5.0.4/build-gromacs/CMakeFiles/CMakeError.log.
 
 -- 
 -
 Rose
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Re: [gmx-users] Jump in temperature each time a new simulation is started.

2014-12-31 Thread Dan Sponseller
Thank you for getting back to me. I understand the limited precision of the 
.gro file but it cannot explain such a large jump in the temperature. Other 
than the fact that I am starting a new simulation, the parameters in the .mdp 
file are the same as the ones that equilibrated and produced the .gro file. 
Below is my .mdp file.

Thank you again.

Daniel Sponseller
PhD Candidate
George Mason University



; This mdp file is for an NPT ensemble.

** Run Control **
integrator   = md
dt   = 0.5
nsteps   = 70
comm-mode= Linear
nstcomm  = 50

** Output Control **
nstxout  = 1
nstvout  = 0
nstfout  = 0
nstlog   = 1000
nstcalcenergy= 20
nstenergy= 20
energygrps   = System

** Neighbor Searching **
cutoff-scheme= Verlet
nstlist  = 40
nstcalclr= -1
ns_type  = grid
pbc  = xyz
periodic-molecules   = no
rlist= 4.0
rlistlong= -1
verlet-buffer-drift  = -1

** Electrostatics **
coulombtype  = PME
coulomb-modifier = Potential-shift
rcoulomb = 3.8

** VdW **
vdwtype  = Cut-off
vdw-modifier = Potential-shift
rvdw = 3.8

** Ewald **
fourierspacing   = 0.15
pme-order= 6
ewald-rtol   = 1e-5

** Temperature Coupling **
tcoupl   = v-rescale
nsttcouple   = -1
tc-grps  = System
tau-t= 1.0
ref-t= 400

** Pressure Coupling **
;pcoupl   = no
pcoupl   = berendsen
pcoupltype   = isotropic
nstpcouple   = -1
tau-p= 2.0
compressibility  = 4.5e-5
ref-p= 1
refcoord-scaling = all

** Velocity Generation **
gen-vel  = no
gen-temp = 400
gen-seed = 4242

** Bonds **
constraints  = none
morse= yes












 On Dec 31, 2014, at 3:07 PM, Justin Lemkul jalem...@vt.edu wrote:
 
 
 
 On 12/31/14 3:05 PM, Dan Sponseller wrote:
 Hello.
 
 Every time I start a new simulation from a conformation that has been well 
 equilibrated, there is a jump in the temperature. For example, starting from 
 a .gro file with velocities that was a well equilibrated system at 400K has 
 initial temperature about 440K.
 
 I am not generating new velocities for the new simulation. This happens all 
 the time. It is always about a 10% increase in the temperature.
 
 Has anyone else experienced this? Does anyone know what might be happening?
 
 
 Please post your full .mdp file; there are options relevant to proper 
 continuation.  Also, velocities in .gro files are limited in precision.  It 
 is much more reliable to restart using a checkpoint file (grompp -t *.cpt).
 
 -Justin
 
 -- 
 ==
 
 Justin A. Lemkul, Ph.D.
 Ruth L. Kirschstein NRSA Postdoctoral Fellow
 
 Department of Pharmaceutical Sciences
 School of Pharmacy
 Health Sciences Facility II, Room 629
 University of Maryland, Baltimore
 20 Penn St.
 Baltimore, MD 21201
 
 jalem...@outerbanks.umaryland.edu | (410) 706-7441
 http://mackerell.umaryland.edu/~jalemkul
 
 ==
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Re: [gmx-users] NPT Simulation average pressure lower than Reference set pressure

2014-10-30 Thread Dan Sponseller
I would recommend 200,000 time steps to try to get accurate pressure readings. 
Pressure, I believe, is computed from the virial and can fluctuate a lot.

Also, adjust nstcalcenergy and nstenergy to a small number, I use 10 to get 
more accurate pressure readings. You should have noticed the error estimate on 
your pressure is 6.2. That could put your actual pressure at 1.

Dan Sponseller
PhD student
George Mason University


 On Oct 30, 2014, at 1:49 AM, Agnivo Gosai agnivogromac...@gmail.com wrote:
 
 Dear Users
 
 I have a DNA-Protein system and I use AMBER99SB-Parmbsc0 ff in GROMACS
 4.5.7 single precision.
 
 My earlier work flow
 1) Topology preparation
 2) Box , Solvation and Ions
 3) Energy minimization - Steepest descent
 4) NVT equilibration using a V-rescale thermostat and ref temp = 300 K
 average temp = 299.7 K after 100 ps NVT sim.
 5) Next is NPT sim ( with same thermostat on )
 
 *Pressure Coupling part of npt.mdp file :*
 
 ; Pressure coupling is on
 pcoupl  = Berendsen ; Pressure coupling on in NPT, also
 weak coupling
 pcoupltype  = isotropic ; uniform scaling of x-y-z box vectors
 tau_p   = 2.0   ; time constant, in ps
 ref_p   = 1.0   ; reference pressure (in bar)
 compressibility = 4.5e-5; isothermal compressibility, bar^-1
 refcoord_scaling= com
 
 
 *Content of npt.log file :*
 
 Last step --- 
 
 Energies (kJ/mol)
  AngleProper Dih.  Improper Dih.  LJ-14 Coulomb-14
1.05446e+041.32866e+046.07202e+025.40636e+034.12184e+04
LJ (SR)  Disper. corr.   Coulomb (SR)   Coul. recip. Position Rest.
1.46731e+05   -1.93498e+03   -1.23170e+06   -1.17442e+051.30130e+03
  PotentialKinetic En.   Total EnergyTemperature Pres. DC (bar)
   -1.13198e+062.06576e+05   -9.25405e+052.99973e+02   -7.72790e+01
 Pressure (bar)   Constr. rmsd
   -5.57060e+000.0e+00
 
 *g_energy output of npt.edr :*
 
 A)​Statistics over 50001 steps [ 0. through 100. ps ], 1 data sets
 All statistics are over 10001 points
 
 Energy  Average   Err.Est.   RMSD  Tot-Drift
 --
 -
 Pressure-5.57066.284.808538.1219  (bar)
 
 (B)All statistics are over 10001 points
 
 Energy  Average   Err.Est.   RMSD  Tot-Drift
 --
 -
 Density 1012.13   0.551.871723.17412
 (kg/m^3)
 
 
 *My run parameters are :*
 ; Run parameters
 integrator  = md; leap-frog integrator
 nsteps  = 5 ; 2 * 5 = 100 ps
 dt  = 0.002 ; 2 fs
 
 My reference pressure is 1 bar , the average pressure is -5.5 bar . I
 believe that the system failed to achieve the reference set pressure.
 
 
 *So should I carry out the simulation for a longer time ?? Or should I use
 a different barostat on the next NPT run or do it in a fresh NPT run.*
 
 *Kindly suggest.*
 
 
 Thanks  Regards
 Agnivo Gosai
 Grad Student, Iowa State University.
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[gmx-users] Bond Energy question.

2014-09-11 Thread Dan Sponseller
Hello.

I have completed a simulation with two polyethylene glycol (PEG) molecules and 
then minimized the final conformation. As a demonstration that the two 
molecules wish to stick together, I separate the two molecules manually and run 
a single minimization step. I inspect the energy log file since it reports the 
energies at step zero. I show that the Potential energy is higher in the 
separated molecules which completes the demonstration.

However, I also notice that the G96Bond energy is almost double. Since the 
atoms within each molecule have not moved relative to each other at step zero, 
should not the bond energy not have changed? The G96Bond energy should just be 
reporting the interaction between bonded atoms, correct?

Thanks for any insight.

Dan Sponseller
PhD student
George Mason University
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[gmx-users] Positive Potential Energy.

2014-08-28 Thread Dan Sponseller
Hello everyone.

I am still fairly new to gromcs but I have researched this well.

I am getting a positive potential energy (my bond energy is always positive) no 
matter how long I run my simulation. I also get this when doing minimizations. 
Even just one molecule set at know minimum conformation. 

I am running in vacuo with no pbc. I have read on the mail list that in vacuo 
can produce this? This doesn’t make sense as the molecule should fly apart with 
always positive PE.

I have tried gromos ff and opsla ff. Both do this. A colleague of mine also  
gets this with his simulations although he reports negative potential when 
solvated.

Any help would be appreciated or any explanation on how to interpret gromacs 
output on this.

I would question gromacs’ abilities if it cannot give a reasonable potential 
energy for a simple system.

Daniel Sponseller
PhD student
George Mason University
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Re: [gmx-users] Gromacs 5.0 installation

2014-08-07 Thread Dan Sponseller
Hello. Just take the .tar.gz on a thumb drive to your new machine and install 
from that.

Note that this machine will already need to have all the prerequisites. If not, 
you will need to install those first:
cmake
gcc

Don’t forget fftw lapack and blas. You can use the ones built in gromacs with 
appropriate cmake flags but they are slow.

Dan
GMU



On Aug 7, 2014, at 2:01 AM, Fatemeh Dabbagh daba...@sums.ac.ir wrote:

 
 
 Hi everyone, 
 
 I'm trying to install Gromacs 5.0 on a computer which has no network
 connection. 
 
 It would be appreciated if some one tell me how this can be done! 
 
 Regards 
 
 Fatemeh 
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[gmx-users] Difficulty preparing a polymer (PEG) for simulation.

2014-03-27 Thread Dan Sponseller
I’m trying to prepare PEG for simulation in gromacs and running into 
considerable difficulties. My PEG chain is

HOC-COC-COC…...COC-COC-COH

with appropriate hydrogens on the carbons. I am using the new CHARM36.ff 
Following the procedure for polymers, I added a beginning, and end, and a 
central chain piece to ‘merged.rtp’ and modified the atom names in the .pdb 
file to match. I have also added the residues to the ‘residuetypes.dat’ as 
Non-Protein (I have also tried listing it as a Protein). 

pdb2gmx claims I have169 missing atoms but will create the .gro and .top files 
anyway with the -missing parameter passed. The .gro file has all the atoms but 
the .top seems to be missing much information on bonds and angles. Probably no 
point in continuing but after a quick editconfig, grompp gives me a fatal 
error: Group Protein referenced in the .mdp file was not found in the index 
file.

I am new to gromacs and would really appreciate help getting started on its use 
like this. Following is some of my data files.

Daniel Sponseller
PhD student
Computational Science and Informatics
George Mason University




Snip from ‘merged.rtp’

;Dan Sponseller
;Copying from DME below for the repeating chain for PEG.
[ LIG ]
  [ atoms ]
   C1 CC32A   -0.010  0
  H11 HCA2A0.090  1
  H12 HCA2A0.090  2
  OO2 OC30A   -0.340  3
   C3 CC32A   -0.010  4
  H31 HCA2A0.090  5
  H32 HCA2A0.090  6
  [ bonds ]
   C1   -C3
   C1   H11
   C1   H12
   C1   OO2
  OO2C3
   C3   H31
   C3   H32
   C3   +C1

;Dan Sponseller
;Next, define begining of chain for PEG. CH2-OH from [ ETOH ]
[ LIGb ]
  [ atoms ]
  OO1 OG311   -0.650  0
  H11  HGP10.420  1
   C3 CG3210.050  2
  H31  HGA20.090  3
  H32  HGA20.090  4
  [ bonds ]
  OO1   H11
  OO1C3
   C3   H31
   C3   H32
   C3   +C1

;Dan Sponseller
;Next, define ending of chain for PEG. CH2-OH from [ ETOH ]
[ LIGe ]
  [ atoms ]
   C1 CG3210.050  0
  H11  HGA20.090  1
  H12  HGA20.090  2
  OO2 OG311   -0.650  3
  H21  HGP10.420  4
  [ bonds ]
   C1   -C3
   C1   H11
   C1   H12
   C1   OO2
  OO2   H21


my modified ‘PEG.pdb’ file:

COMPNDUNNAMED
AUTHORGENERATED BY OPEN BABEL 
HETATM1   C1 LIGe1 -14.784  -1.665   0.506  1.00  0.00   C  
HETATM2   C3 LIG 2 -13.927  -1.410  -0.735  1.00  0.00   C  
HETATM3  OO2 LIG 2 -13.056  -0.302  -0.493  1.00  0.00   O  
HETATM4  H11 LIGe1 -15.383  -2.563   0.355  1.00  0.00   H
HETATM5  H12 LIGe1 -14.137  -1.802   1.372  1.00  0.00   H
HETATM6  H31 LIG 2 -13.333  -2.297  -0.956  1.00  0.00   H
HETATM7  H32 LIG 2 -14.573  -1.185  -1.584  1.00  0.00   H
HETATM8   C1 LIG 2 -12.207   0.022  -1.596  1.00  0.00   C  
HETATM9   C3 LIG 3 -11.325   1.216  -1.227  1.00  0.00   C  
HETATM   10  OO2 LIG 3 -10.441   0.845  -0.167  1.00  0.00   O  
HETATM   11  H12 LIG 2 -11.578  -0.836  -1.835  1.00  0.00   H
HETATM   12  H11 LIG 2 -12.818   0.276  -2.463  1.00  0.00   H
HETATM   13  H31 LIG 3 -10.741   1.519  -2.096  1.00  0.00   H
HETATM   14  H32 LIG 3 -11.953   2.046  -0.903  1.00  0.00   H
HETATM   15   C1 LIG 3  -9.568   1.894   0.257  1.00  0.00   C  
HETATM   16   C3 LIG 4  -8.673   1.387   1.389  1.00  0.00   C  
HETATM   17  OO2 LIG 4  -7.815   0.358   0.894  1.00  0.00   O  
HETATM   18  H11 LIG 3  -8.949   2.211  -0.582  1.00  0.00   H
HETATM   19  H12 LIG 3 -10.160   2.738   0.611  1.00  0.00   H
HETATM   20  H31 LIG 4  -8.070   2.210   1.772  1.00  0.00   H
HETATM   21  H32 LIG 4  -9.294   0.988   2.192  1.00  0.00   H
HETATM   22   C1 LIG 4  -6.933  -0.187   1.877  1.00  0.00   C  
HETATM   23   C3 LIG 5  -6.066  -1.274   1.239  1.00  0.00   C  
HETATM   24  OO2 LIG 5  -5.215  -0.687   0.252  1.00  0.00   O  
HETATM   25  H11 LIG 4  -6.294   0.603   2.270  1.00  0.00   H
HETATM   26  H12 LIG 4  -7.517  -0.619   2.690  1.00  0.00   H
HETATM   27  H32 LIG 5  -5.457  -1.751   2.007  1.00  0.00   H
HETATM   28  H31 LIG 5  -6.707  -2.020   0.768  1.00  0.00   H
HETATM   29   C1 LIG 5  -4.360  -1.621  -0.408  1.00  0.00   C  
HETATM   30   C3 LIG 6  -3.499  -0.885  -1.437