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GMX-CHECK(1)			     GROMACS			    GMX-CHECK(1)

NAME
     gmx-check - Check and compare files

SYNOPSIS
	gmx check [-f [<.xtc/.trr/...>]] [-f2 [<.xtc/.trr/...>]] [-s1 [<.tpr>]]
		  [-s2 [<.tpr>]] [-c [<.tpr/.gro/...>]] [-e [<.edr>]]
		  [-e2 [<.edr>]] [-n [<.ndx>]] [-m [<.tex>]] [-vdwfac <real>]
		  [-bonlo <real>] [-bonhi <real>] [-[no]rmsd] [-tol <real>]
		  [-abstol <real>] [-[no]ab] [-lastener <string>]

DESCRIPTION
     gmx check reads a trajectory (.tng, .trr or .xtc), an energy file (.edr) or
     an index file (.ndx) and prints out useful information about them.

     Option  -c  checks  for  presence of coordinates, velocities and box in the
     file, for close contacts (smaller than -vdwfac and not bonded, i.e. not be-
     tween -bonlo and -bonhi, all relative to the sum  of  both  Van  der  Waals
     radii)  and  atoms  outside the box (these may occur often and are no prob-
     lem). If velocities are present, an estimated temperature	will  be  calcu-
     lated from them.

     If an index file, is given its contents will be summarized.

     If  both a trajectory and a .tpr file are given (with -s1) the program will
     check whether the bond lengths defined in the tpr file are  indeed  correct
     in  the  trajectory.  If  not  you  may have non-matching files due to e.g.
     deshuffling or due to problems with virtual sites. With  these  flags,  gmx
     check provides a quick check for such problems.

     The  program  can	compare two run input (.tpr) files when both -s1 and -s2
     are supplied. When comparing run input files this way, the default relative
     tolerance is reduced to 0.000001 and the absolute tolerance set to zero  to
     find  any	differences  not due to minor compiler optimization differences,
     although you can of course still set any other tolerances through	the  op-
     tions.  Similarly a pair of trajectory files can be compared (using the -f2
     option), or a pair of energy files (using the -e2 option).

     For  free	energy simulations the A and B state topology from one run input
     file can be compared with options -s1 and -ab.

OPTIONS
     Options to specify input files:

     -f [<.xtc/.trr/...>] (traj.xtc) (Optional)
	    Trajectory: xtc trr cpt gro g96 pdb tng h5md

     -f2 [<.xtc/.trr/...>] (traj.xtc) (Optional)
	    Trajectory: xtc trr cpt gro g96 pdb tng h5md

     -s1 [<.tpr>] (top1.tpr) (Optional)
	    Portable xdr run input file

     -s2 [<.tpr>] (top2.tpr) (Optional)
	    Portable xdr run input file

     -c [<.tpr/.gro/...>] (topol.tpr) (Optional)
	    Structure+mass(db): tpr gro g96 pdb brk ent

     -e [<.edr>] (ener.edr) (Optional)
	    Energy file

     -e2 [<.edr>] (ener2.edr) (Optional)
	    Energy file

     -n [<.ndx>] (index.ndx) (Optional)
	    Index file

     Options to specify output files:

     -m [<.tex>] (doc.tex) (Optional)
	    LaTeX file

     Other options:

     -vdwfac <real> (0.8)
	    Fraction of sum of VdW radii used as warning cutoff

     -bonlo <real> (0.4)
	    Min. fract. of sum of VdW radii for bonded atoms

     -bonhi <real> (0.7)
	    Max. fract. of sum of VdW radii for bonded atoms

     -[no]rmsd (no)
	    Print RMSD for x, v and f

     -tol <real> (0.001)
	    Relative  tolerance   for	comparing   real   values   defined   as
	    2*(a-b)/(|a|+|b|)

     -abstol <real> (0.001)
	    Absolute tolerance, useful when sums are close to zero.

     -[no]ab (no)
	    Compare the A and B topology from one file

     -lastener <string>
	    Last  energy term to compare (if not given all are tested). It makes
	    sense to go up until the Pressure.

SEE ALSO
     gmx(1)

     More information about GROMACS is available at <http://www.gromacs.org/>.

COPYRIGHT
     2026, GROMACS development team

2026.3				  Jun 25, 2026			    GMX-CHECK(1)

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