Da-Wei Li wrote:
hi, all

I get another strange error. Once I turn on free energy calculation. mdrun will complain this:

Initial maximum inter charge-group distances:
    two-body bonded interactions: 4.509 nm, LJC Pairs NB, atoms 1013 1231
  multi-body bonded interactions: 0.428 nm, Proper Dih., atoms 5 13
Minimum cell size due to bonded interactions: 4.960 nm


It looks like your topology has some serious problems. Bonded interactions should not occur at 4-nm distance, unless you're using some special distance restraints, in which case you probably can't make DD work very efficiently; mdrun -pd might be an option in that case. If you're running a basic protein simulation without special restraints, etc then something is wrong in the topology.


so that domain decomposition will not work. What is a LJC pair? I did

Some sort of 1-4 interaction, it looks like, but I didn't spend much time in the code to be absolutely sure.

-Justin

not see any problem with my system. Everything is fine if free_energy = no.

thanks.

dawei



On Mon, Feb 7, 2011 at 1:38 PM, Da-Wei Li <lida...@gmail.com <mailto:lida...@gmail.com>> wrote:

    hello

    My goal is to study the solvation free energy of a fixed protein and
    compare it with implicit model. The pr1. mdp is just a test case.
    Grompp always need more than 10 minutes to finish for my 76 residues
    protein when free_energy = yes, no matter there is PR or not,
    whether I switch off only vdm or switch both ele and vdm.

    The memory usage is <1% on a system with 16GB memory so that memory
    limitation can be ruled out.

    best,

    dawei



    On Mon, Feb 7, 2011 at 1:31 PM, TJ Mustard <musta...@onid.orst.edu
    <mailto:musta...@onid.orst.edu>> wrote:

        Da-Wei,


        Do you need FEP information on the PR step? Are you going to do
        a MD(sd) with FEP on after the PR?

        And are you doing hydration of a protein?

Thank you,
        TJ Mustard

        On February 7, 2011 at 10:23 AM "Justin A. Lemkul"
        <jalem...@vt.edu <mailto:jalem...@vt.edu>> wrote:

         >
         >
         > Da-Wei Li wrote:
         > > hello
         > >
         > > Here they are the command line and mdp file. I use Gromacs
        4.5.3. This
         > > is a test case only and the protein is 1UBQ. Grompp wills
        top for about
         > > 10 minutes then go through.
         > >
         >
         > The efficiency of this kind of process will depend on the
        amount of available
         > memory on the system.  You're asking grompp to decouple a
        huge amount of degrees
         > of freedom, which will require a lot of memory to do.  It
        sounds like it's
         > working, in any case, so there's no real problem.
         >
         > Whether or not simultaneously decoupling the LJ and Coulombic
        interactions of a
         > whole protein will generate a stable trajectory or sensible
        result is another
         > matter.
         >
         > -Justin
         >
         > > ***********output of grompp*****************
         > >
         > > Back Off! I just backed up mdout.mdp to ./#mdout.mdp.6#
         > > Generated 2278 of the 2278 non-bonded parameter combinations
         > > Generating 1-4 interactions: fudge = 0.5
         > > Generated 2278 of the 2278 1-4 parameter combinations
         > > Excluding 3 bonded neighbours molecule type 'Protein'
         > > turning H bonds into constraints...
         > > Excluding 2 bonded neighbours molecule type 'SOL'
         > > turning H bonds into constraints...
         > > Coupling 1 copies of molecule type 'Protein'
         > > Setting gen_seed to 8552
         > > Velocities were taken from a Maxwell distribution at 300 K
         > > ********************************
         > >
         > > Command line and mdp file:
         > >
         > > ******************************
         > > grompp -f pr1.mdp -c after_em.gro -t em.trr -p topol.top -o pr1
         > > ******************************
         > > define = -DPOSRES ; position restrain the protein
         > > ; Run parameters
         > > integrator = sd ; leap-frog integrator
         > > nsteps = 5000 ; 2 * 50000 = 100 ps
         > > dt = 0.002 ; 2 fs
         > > ; Output control
         > > nstxout = 1000 ; save coordinates every 2 ps
         > > nstvout = 5000 ; save velocities every 100ps
         > > nstenergy = 1000 ; save energies every 2 ps
         > > nstlog = 1000 ; update log file every 2 ps
         > > ; Bond parameters
         > > continuation = no ; first dynamics run
         > > constraint_algorithm = lincs ; holonomic constraints
         > > constraints = hbonds ; H bonds constrained
         > > lincs_iter = 1 ; accuracy of LINCS
         > > lincs_order = 4 ; also related to accuracy
         > > ; Neighborsearching
         > > ns_type = grid ; search neighboring grid cels
         > > nstlist = 10 ; 20 fs
         > > rlist = 0.8 ; short-range neighborlist cutoff (in nm)
         > > rcoulomb = 0.8 ; short-range electrostatic cutoff (in nm)
         > > rvdw = 1.0 ; short-range van der Waals cutoff (in nm)
         > > ; Electrostatics
         > > coulombtype = PME ; Particle Mesh Ewald for long-range
        electrostatics
         > > pme_order = 4 ; cubic interpolation
         > > fourierspacing = 0.12 ; grid spacing for FFT
         > > ; Temperature coupling is on
         > > tcoupl = V-rescale ; modified Berendsen thermostat
         > > tc-grps = Protein Non-Protein ; two coupling groups - more
        accurate
         > > tau_t = 0.1 0.1 ; time constant, in ps
         > > ref_t = 300 300 ; reference temperature, one for each
        group, in K
         > > ; Pressure coupling is off
         > > pcoupl = no ; no pressure coupling in NVT
         > > ; Periodic boundary conditions
         > > pbc = xyz ; 3-D PBC
         > > ; Dispersion correction
         > > DispCorr = EnerPres ; account for cut-off vdW scheme
         > > ; Velocity generation
         > > gen_vel = yes ; assign velocities from Maxwell distribution
         > > gen_temp = 300 ; temperature for Maxwell distribution
         > > gen_seed = -1 ; generate a random seed
         > > ;free energy stuff
         > > free_energy              = yes
         > > init_lambda              = 0.0
         > > delta_lambda             = 0
         > > sc_alpha                 =0.5
         > > sc-power                 =1.0
         > > sc-sigma                 = 0.3
         > > couple-moltype           = Protein
         > > couple-lambda0           = vdw-q
         > > couple-lambda1           = none
         > > *******************************
         > >
         > > thanks.
         > >
         > > dawei
         > >
         > >
         > >
         > >
         > > On Mon, Feb 7, 2011 at 1:05 PM, TJ Mustard
        <musta...@onid.orst.edu <mailto:musta...@onid.orst.edu>
         > > <mailto:musta...@onid.orst.edu
        <mailto:musta...@onid.orst.edu>>> wrote:
         > >
         > >     Dawei,
         > >
> > > >
         > >     I have no problems with proteins in the thousands of
        atoms. Can you
         > >     post your command line and mdp files?
         > >
> > > >
         > >     Thank you,
         > >
         > >     TJ Mustard
         > >
         > >
         > >     On February 7, 2011 at 9:31 AM Da-Wei Li
        <lida...@gmail.com <mailto:lida...@gmail.com>
         > >     <mailto:lida...@gmail.com <mailto:lida...@gmail.com>>>
        wrote:
         > >
         > >>     Well. It  actually isn't dead but becomes very slow
        for large
         > >>     proteins.   dawei
         > >>
         > >>     On Mon, Feb 7, 2011 at 11:44 AM, Da-Wei Li
        <lida...@gmail.com <mailto:lida...@gmail.com>
         > >>     <mailto:lida...@gmail.com <mailto:lida...@gmail.com>>>
        wrote:
         > >>
         > >>         hi,
         > >>         I did more test and found that it depended on size
        of the
         > >>         protein. Grompp will die when number of atoms of
        the protein
         > >>         is larger than about 200. Is it possible the
        source code limit
         > >>         the size of the protein that can be decoupled?
         > >>         thanks.
         > >>         dawei
         > >>
         > >>
         > >>         On Mon, Feb 7, 2011 at 10:34 AM, Da-Wei Li
        <lida...@gmail.com <mailto:lida...@gmail.com>
         > >>         <mailto:lida...@gmail.com
        <mailto:lida...@gmail.com>>> wrote:
         > >>
         > >>             Dear users
         > >>             I tried free energy calculation but grompp
        couldn't go
         > >>             through. It stops after
         > >>             *******************
         > >>             Generated 2278 of the 2278 non-bonded
        parameter combinations
         > >>             Generating 1-4 interactions: fudge = 0.5
         > >>             Generated 2278 of the 2278 1-4 parameter
        combinations
         > >>             Excluding 3 bonded neighbours molecule type
        'Protein'
         > >>             turning H bonds into constraints...
         > >>             Excluding 2 bonded neighbours molecule type 'SOL'
         > >>             turning H bonds into constraints...
         > >>             Excluding 1 bonded neighbours molecule type 'CL'
         > >>             turning H bonds into constraints...
         > >>             Coupling 1 copies of molecule type 'Protein'
         > >>             *******************
         > >>             The CPU usage is 100%.
         > >>             I just add following into the mdp file:
         > >>             ***************
         > >>             free_energy              = yes
         > >>             init_lambda              = 0.0
         > >>             delta_lambda             = 0
         > >>             sc_alpha                 =0.5
         > >>             sc-power                 =1.0
         > >>             sc-sigma                 = 0.3
> >> couple-moltype = Protein > >> couple-lambda0 = vdw-q
         > >>             couple-lambda1           = none
         > >>             ***************
         > >>             Does anyone have some idea about this
        problem?  thanks.
         > >>             Another question is whether I can switch off "two
         > >>             molecules" (such as protein+ligand) in free energy
         > >>             calculation? I searched this list and got that
        4.0.7 did
         > >>             support this. how about 4.5.4?
         > >>             dawei
         > >>
         > >>
> > > >
         > >     TJ Mustard
         > >     Email: musta...@onid.orst.edu
        <mailto:musta...@onid.orst.edu> <mailto:musta...@onid.orst.edu
        <mailto:musta...@onid.orst.edu>>
         > >
         > >
         > >     --
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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 <http://vt.edu> | (540) 231-9080
         > http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
         >
         > ========================================
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        TJ Mustard
        Email: musta...@onid.orst.edu <mailto:musta...@onid.orst.edu>


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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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