[gmx-users] Test Particle Insertion of Water

Javier Cerezo jcb1 at um.es
Wed May 9 16:01:12 CEST 2012


Sorry, I saw now the command line you've posted. Did you check your trr 
with gmxcheck?

El 09/05/12 15:49, Steven Neumann escribió:
> hello gmx users,
>
> I am sorry for bothering you but I was searching mailing list and no 
> results. I have a problem with my test particle insertion as I run the 
> workflow I described previously with my mdp:
>
> title       = Test Particle Insertion
> ; Run parameters
> integrator  = tpi
> nsteps      = 50000000    ; 100 ns
> dt          = 0.002     ; 2 fs
> ; Output control
> nstxout     = 0          ; suppress .trr output ; output coordinates 
> every 25 ps
> nstvout     = 25000     ; velocities to output every 25000 steps
> nstenergy   = 1000      ; save energies every 2 ps
> nstlog      = 1000      ; update log file every 2 ps
> nstxtcout   = 100000         ; suppress (tlumic) xtc trajectory
> energygrps  = System
> continuation    = no           ; first dynamics run
> constraint_algorithm = lincs    ; holonomic constraints
> constraints     = all-bonds     ; all bonds (even heavy atom-H bonds) 
> constrained
> lincs_iter      = 1             ; accuracy of LINCS
> lincs_order     = 4             ; also related to accuracy
> ; Neighborsearching
> ns_type     = grid      ; search neighboring grid cells
> nstlist     = 5         ; 10 fs
> vdwtype     = Switch
> rvdw-switch = 1.0
> rlist       = 1.4       ; short-range neighborlist cutoff (in nm)
> rcoulomb    = 1.4       ; short-range electrostatic cutoff (in nm)
> rvdw        = 1.2       ; short-range van der Waals cutoff (in nm)
> ewald_rtol  = 1e-5      ; relative strenght of the Ewald-shifted 
> potential rcoulomb
> ; 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     = System                 ; two coupling groups - more accurate
> tau_t       = 0.1                             ; time constant, in ps
> ref_t       = 318                         ; reference temperature, one 
> for each group, in K
> ; Pressure coupling is on
> pcoupl      = Parrinello-Rahman             ; pressure coupling is on 
> for NPT
> pcoupltype  = isotropic                     ; uniform scaling of box 
> vectors
> tau_p       = 2.0                           ; time constant, in ps
> ref_p       = 1.0                           ; reference pressure, in bar
> compressibility = 4.5e-5                    ; isothermal 
> compressibility of water, bar^-1
> ; 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    = 318       ; temperature for Maxwell distribution
> gen_seed    = -1        ; generate a random seed
>
> Then My log file:
>
>
>  The temperature for test particle insertion is 318.000 K
>
> Started Test Particle Insertion on node 0 Wed May  9 14:18:18 2012
>
> Will insert 3 atoms with partial charges
>
> Will insert 50000000 times in each frame of md318.trr
> Will use the same neighborlist for 5 insertions in a sphere of radius 
> 0.050000
>
> <V>  =         -nan nm^3
> <mu> =         -nan kJ/mol
> No MEGA Flopsen this time
>
>      R E A L   C Y C L E   A N D   T I M E   A C C O U N T I N G
>
>  Computing:         Nodes     Number     G-Cycles    Seconds     %
> ------------------------------
> -----------------------------------------
>  Rest                   4                   5.218        1.9   100.0
> -----------------------------------------------------------------------
>  Total                  4                   5.218        1.9   100.0
> -----------------------------------------------------------------------
>
>     Parallel run - timing based on wallclock.
>
>                NODE (s)   Real (s)      (%)
>        Time:      0.485      0.485    100.0
>                (Mnbf/s)   (MFlops)   (steps/hour)
> Performance:      0.000      0.000            0.0
> Finished mdrun on node 0 Wed May  9 14:18:19 2012
>
>
>
> Files are empty. Do you have any clue what is happening?
>
> Thank you for your time,
>
> Steven
>
>
> On Wed, May 9, 2012 at 1:45 PM, Javier Cerezo <jcb1 at um.es 
> <mailto:jcb1 at um.es>> wrote:
>
>     Hi Steven
>
>     As I remember, TPI is based on the calculation of the potential at
>     every conformation from the already computed simulation (inserting
>     the particle in every snapshot), so velocities are not used.
>
>     Anyway, use both and see if there are any differences.
>
>     Javier
>
>     El 09/05/12 11:27, Steven Neumann escribió:
>>     Dear Gmx Users,
>>
>>     I am running TPI of the water in the system containing free amino
>>     acids. Steps:
>>
>>     1. I run the NPT simulation of 100 ns to equilibrate the system.
>>     2. I added 1 extra water molecule to the final pdb file
>>     (converted from gro) and to topology
>>     3. I creaded tpi.tpr using grompp using new pdb file with extra
>>     water molecule
>>     4. mdrun --s tpi298.tpr -rerun md298.trr -deffnm tpi298 -tpi
>>     tpi298.xvg -tpid tpid298.xvg
>>
>>     My question: Is it better generate new velocities in my mdp file
>>     (continuation = yes, gen_vel = no, tpi integrator) for a pdb file
>>     or use velocities from previous simulations (gro file)?
>>     If the second option is more appropriate what velocity shall I
>>     adjust to the extra water molecule?
>>
>>     I will appreciate your reply.
>>
>>     Steven
>>
>>
>
>     -- 
>     Javier CEREZO BASTIDA
>     PhD Student
>     Physical Chemistry
>     Universidad de Murcia
>     Murcia (Spain)
>     Tel: (+34)868887434 <tel:%28%2B34%29868887434>
>
>     --
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>
>
>

-- 
Javier CEREZO BASTIDA
PhD Student
Physical Chemistry
Universidad de Murcia
Murcia (Spain)
Tel: (+34)868887434
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