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NAME
gmx-mdrun - Perform a simulation, do a normal mode analysis or an energy minimization
SYNOPSIS
gmx mdrun [-s [<.tpr>]] [-cpi [<.cpt>]] [-table [<.xvg>]]
[-tabletf [<.xvg>]] [-tablep [<.xvg>]] [-tableb [<.xvg>]]
[-rerun [<.xtc/.trr/...>]] [-ei [<.edi>]]
[-multidir [<dir> [...]]] [-membed [<.dat>]] [-mp [<.top>]]
[-mn [<.ndx>]] [-o [<.trr/.cpt/...>]] [-x [<.xtc/.tng>]]
[-cpo [<.cpt>]] [-c [<.gro/.g96/...>]] [-e [<.edr>]]
[-g [<.log>]] [-dhdl [<.xvg>]] [-field [<.xvg>]]
[-tpi [<.xvg>]] [-tpid [<.xvg>]] [-eo [<.xvg>]]
[-devout [<.xvg>]] [-runav [<.xvg>]] [-px [<.xvg>]]
[-pf [<.xvg>]] [-ro [<.xvg>]] [-ra [<.log>]] [-rs [<.log>]]
[-rt [<.log>]] [-mtx [<.mtx>]] [-dn [<.ndx>]]
[-if [<.xvg>]] [-swap [<.xvg>]] [-deffnm <string>]
[-xvg <enum>] [-dd <vector>] [-ddorder <enum>]
[-npme <int>] [-nt <int>] [-ntmpi <int>] [-ntomp <int>]
[-ntomp_pme <int>] [-pin <enum>] [-pinoffset <int>]
[-pinstride <int>] [-gpu_id <string>] [-[no]ddcheck]
[-rdd <real>] [-rcon <real>] [-dlb <enum>] [-dds <real>]
[-gcom <int>] [-nb <enum>] [-nstlist <int>] [-[no]tunepme]
[-[no]v] [-[no]compact] [-pforce <real>] [-[no]reprod]
[-cpt <real>] [-[no]cpnum] [-[no]append] [-nsteps <int>]
[-maxh <real>] [-multi <int>] [-replex <int>] [-nex <int>]
[-reseed <int>]
DESCRIPTION
gmx mdrun is the main computational chemistry engine within GROMACS. Obviously, it
performs Molecular Dynamics simulations, but it can also perform Stochastic Dynamics,
Energy Minimization, test particle insertion or (re)calculation of energies. Normal mode
analysis is another option. In this case mdrun builds a Hessian matrix from single
conformation. For usual Normal Modes-like calculations, make sure that the structure
provided is properly energy-minimized. The generated matrix can be diagonalized by gmx
nmeig.
The mdrun program reads the run input file (-s) and distributes the topology over ranks if
needed. mdrun produces at least four output files. A single log file (-g) is written.
The trajectory file (-o), contains coordinates, velocities and optionally forces. The
structure file (-c) contains the coordinates and velocities of the last step. The energy
file (-e) contains energies, the temperature, pressure, etc, a lot of these things are
also printed in the log file. Optionally coordinates can be written to a compressed
trajectory file (-x).
The option -dhdl is only used when free energy calculation is turned on.
Running mdrun efficiently in parallel is a complex topic topic, many aspects of which are
covered in the online User Guide. You should look there for practical advice on using many
of the options available in mdrun.
ED (essential dynamics) sampling and/or additional flooding potentials are switched on by
using the -ei flag followed by an .edi file. The .edi file can be produced with the
make_edi tool or by using options in the essdyn menu of the WHAT IF program. mdrun
produces a .xvg output file that contains projections of positions, velocities and forces
onto selected eigenvectors.
When user-defined potential functions have been selected in the .mdp file the -table
option is used to pass mdrun a formatted table with potential functions. The file is read
from either the current directory or from the GMXLIB directory. A number of pre-formatted
tables are presented in the GMXLIB dir, for 6-8, 6-9, 6-10, 6-11, 6-12 Lennard-Jones
potentials with normal Coulomb. When pair interactions are present, a separate table for
pair interaction functions is read using the -tablep option.
When tabulated bonded functions are present in the topology, interaction functions are
read using the -tableb option. For each different tabulated interaction type the table
file name is modified in a different way: before the file extension an underscore is
appended, then a 'b' for bonds, an 'a' for angles or a 'd' for dihedrals and finally the
table number of the interaction type.
The options -px and -pf are used for writing pull COM coordinates and forces when pulling
is selected in the .mdp file.
Finally some experimental algorithms can be tested when the appropriate options have been
given. Currently under investigation are: polarizability.
The option -membed does what used to be g_membed, i.e. embed a protein into a membrane.
This module requires a number of settings that are provided in a data file that is the
argument of this option. For more details in membrane embedding, see the documentation in
the user guide. The options -mn and -mp are used to provide the index and topology files
used for the embedding.
The option -pforce is useful when you suspect a simulation crashes due to too large
forces. With this option coordinates and forces of atoms with a force larger than a
certain value will be printed to stderr.
Checkpoints containing the complete state of the system are written at regular intervals
(option -cpt) to the file -cpo, unless option -cpt is set to -1. The previous checkpoint
is backed up to state_prev.cpt to make sure that a recent state of the system is always
available, even when the simulation is terminated while writing a checkpoint. With -cpnum
all checkpoint files are kept and appended with the step number. A simulation can be
continued by reading the full state from file with option -cpi. This option is intelligent
in the way that if no checkpoint file is found, GROMACS just assumes a normal run and
starts from the first step of the .tpr file. By default the output will be appending to
the existing output files. The checkpoint file contains checksums of all output files,
such that you will never loose data when some output files are modified, corrupt or
removed. There are three scenarios with -cpi:
* no files with matching names are present: new output files are written
* all files are present with names and checksums matching those stored in the checkpoint
file: files are appended
* otherwise no files are modified and a fatal error is generated
With -noappend new output files are opened and the simulation part number is added to all
output file names. Note that in all cases the checkpoint file itself is not renamed and
will be overwritten, unless its name does not match the -cpo option.
With checkpointing the output is appended to previously written output files, unless
-noappend is used or none of the previous output files are present (except for the
checkpoint file). The integrity of the files to be appended is verified using checksums
which are stored in the checkpoint file. This ensures that output can not be mixed up or
corrupted due to file appending. When only some of the previous output files are present,
a fatal error is generated and no old output files are modified and no new output files
are opened. The result with appending will be the same as from a single run. The
contents will be binary identical, unless you use a different number of ranks or dynamic
load balancing or the FFT library uses optimizations through timing.
With option -maxh a simulation is terminated and a checkpoint file is written at the first
neighbor search step where the run time exceeds -maxh*0.99 hours. This option is
particularly useful in combination with setting nsteps to -1 either in the mdp or using
the similarly named command line option. This results in an infinite run, terminated only
when the time limit set by -maxh is reached (if any)or upon receiving a signal.
When mdrun receives a TERM signal, it will set nsteps to the current step plus one. When
mdrun receives an INT signal (e.g. when ctrl+C is pressed), it will stop after the next
neighbor search step (with nstlist=0 at the next step). In both cases all the usual
output will be written to file. When running with MPI, a signal to one of the mdrun ranks
is sufficient, this signal should not be sent to mpirun or the mdrun process that is the
parent of the others.
Interactive molecular dynamics (IMD) can be activated by using at least one of the three
IMD switches: The -imdterm switch allows one to terminate the simulation from the
molecular viewer (e.g. VMD). With -imdwait, mdrun pauses whenever no IMD client is
connected. Pulling from the IMD remote can be turned on by -imdpull. The port mdrun
listens to can be altered by -imdport.The file pointed to by -if contains atom indices and
forces if IMD pulling is used.
When mdrun is started with MPI, it does not run niced by default.
OPTIONS
Options to specify input files:
-s [<.tpr>] (topol.tpr)
Portable xdr run input file
-cpi [<.cpt>] (state.cpt) (Optional)
Checkpoint file
-table [<.xvg>] (table.xvg) (Optional)
xvgr/xmgr file
-tabletf [<.xvg>] (tabletf.xvg) (Optional)
xvgr/xmgr file
-tablep [<.xvg>] (tablep.xvg) (Optional)
xvgr/xmgr file
-tableb [<.xvg>] (table.xvg) (Optional)
xvgr/xmgr file
-rerun [<.xtc/.trr/...>] (rerun.xtc) (Optional)
Trajectory: xtc trr cpt gro g96 pdb tng
-ei [<.edi>] (sam.edi) (Optional)
ED sampling input
-multidir [<dir> [...]] (rundir) (Optional)
Run directory
-membed [<.dat>] (membed.dat) (Optional)
Generic data file
-mp [<.top>] (membed.top) (Optional)
Topology file
-mn [<.ndx>] (membed.ndx) (Optional)
Index file
Options to specify output files:
-o [<.trr/.cpt/...>] (traj.trr)
Full precision trajectory: trr cpt tng
-x [<.xtc/.tng>] (traj_comp.xtc) (Optional)
Compressed trajectory (tng format or portable xdr format)
-cpo [<.cpt>] (state.cpt) (Optional)
Checkpoint file
-c [<.gro/.g96/...>] (confout.gro)
Structure file: gro g96 pdb brk ent esp
-e [<.edr>] (ener.edr)
Energy file
-g [<.log>] (md.log)
Log file
-dhdl [<.xvg>] (dhdl.xvg) (Optional)
xvgr/xmgr file
-field [<.xvg>] (field.xvg) (Optional)
xvgr/xmgr file
-tpi [<.xvg>] (tpi.xvg) (Optional)
xvgr/xmgr file
-tpid [<.xvg>] (tpidist.xvg) (Optional)
xvgr/xmgr file
-eo [<.xvg>] (edsam.xvg) (Optional)
xvgr/xmgr file
-devout [<.xvg>] (deviatie.xvg) (Optional)
xvgr/xmgr file
-runav [<.xvg>] (runaver.xvg) (Optional)
xvgr/xmgr file
-px [<.xvg>] (pullx.xvg) (Optional)
xvgr/xmgr file
-pf [<.xvg>] (pullf.xvg) (Optional)
xvgr/xmgr file
-ro [<.xvg>] (rotation.xvg) (Optional)
xvgr/xmgr file
-ra [<.log>] (rotangles.log) (Optional)
Log file
-rs [<.log>] (rotslabs.log) (Optional)
Log file
-rt [<.log>] (rottorque.log) (Optional)
Log file
-mtx [<.mtx>] (nm.mtx) (Optional)
Hessian matrix
-dn [<.ndx>] (dipole.ndx) (Optional)
Index file
-if [<.xvg>] (imdforces.xvg) (Optional)
xvgr/xmgr file
-swap [<.xvg>] (swapions.xvg) (Optional)
xvgr/xmgr file
Other options:
-deffnm <string>
Set the default filename for all file options
-xvg <enum>
xvg plot formatting: xmgrace, xmgr, none
-dd <vector> (0 0 0)
Domain decomposition grid, 0 is optimize
-ddorder <enum> (interleave)
DD rank order: interleave, pp_pme, cartesian
-npme <int> (-1)
Number of separate ranks to be used for PME, -1 is guess
-nt <int> (0)
Total number of threads to start (0 is guess)
-ntmpi <int> (0)
Number of thread-MPI threads to start (0 is guess)
-ntomp <int> (0)
Number of OpenMP threads per MPI rank to start (0 is guess)
-ntomp_pme <int> (0)
Number of OpenMP threads per MPI rank to start (0 is -ntomp)
-pin <enum> (auto)
Whether mdrun should try to set thread affinities: auto, on, off
-pinoffset <int> (0)
The lowest logical core number to which mdrun should pin the first thread
-pinstride <int> (0)
Pinning distance in logical cores for threads, use 0 to minimize the number of
threads per physical core
-gpu_id <string>
List of GPU device id-s to use, specifies the per-node PP rank to GPU mapping
-[no]ddcheck (yes)
Check for all bonded interactions with DD
-rdd <real> (0)
The maximum distance for bonded interactions with DD (nm), 0 is determine from
initial coordinates
-rcon <real> (0)
Maximum distance for P-LINCS (nm), 0 is estimate
-dlb <enum> (auto)
Dynamic load balancing (with DD): auto, no, yes
-dds <real> (0.8)
Fraction in (0,1) by whose reciprocal the initial DD cell size will be increased in
order to provide a margin in which dynamic load balancing can act while preserving
the minimum cell size.
-gcom <int> (-1)
Global communication frequency
-nb <enum> (auto)
Calculate non-bonded interactions on: auto, cpu, gpu, gpu_cpu
-nstlist <int> (0)
Set nstlist when using a Verlet buffer tolerance (0 is guess)
-[no]tunepme (yes)
Optimize PME load between PP/PME ranks or GPU/CPU
-[no]v (no)
Be loud and noisy
-[no]compact (yes)
Write a compact log file
-pforce <real> (-1)
Print all forces larger than this (kJ/mol nm)
-[no]reprod (no)
Try to avoid optimizations that affect binary reproducibility
-cpt <real> (15)
Checkpoint interval (minutes)
-[no]cpnum (no)
Keep and number checkpoint files
-[no]append (yes)
Append to previous output files when continuing from checkpoint instead of adding
the simulation part number to all file names
-nsteps <int> (-2)
Run this number of steps, overrides .mdp file option (-1 means infinite, -2 means
use mdp option, smaller is invalid)
-maxh <real> (-1)
Terminate after 0.99 times this time (hours)
-multi <int> (0)
Do multiple simulations in parallel
-replex <int> (0)
Attempt replica exchange periodically with this period (steps)
-nex <int> (0)
Number of random exchanges to carry out each exchange interval (N^3 is one
suggestion). -nex zero or not specified gives neighbor replica exchange.
-reseed <int> (-1)
Seed for replica exchange, -1 is generate a seed
SEE ALSO
gmx(1)
More information about GROMACS is available at <http://www.gromacs.org/>.
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2015, GROMACS development team