Provided by: gromacs-data_2025.2-1_all 
NAME
gmx-rmsf - Calculate atomic fluctuations
SYNOPSIS
gmx rmsf [-f [<.xtc/.trr/...>]] [-s [<.tpr/.gro/...>]] [-n [<.ndx>]]
[-q [<.pdb>]] [-oq [<.pdb>]] [-ox [<.pdb>]] [-o [<.xvg>]]
[-od [<.xvg>]] [-oc [<.xvg>]] [-dir [<.log>]] [-b <time>]
[-e <time>] [-dt <time>] [-[no]w] [-xvg <enum>] [-[no]res]
[-[no]aniso] [-[no]fit]
DESCRIPTION
gmx rmsf computes the root mean square fluctuation (RMSF, i.e. standard deviation) of atomic positions in
the trajectory (supplied with -f) after (optionally) fitting to a reference frame (supplied with -s).
With option -oq the RMSF values are converted to B-factor values, which are written to a .pdb file. By
default, the coordinates in this output file are taken from the structure file provided with -s,although
you can also use coordinates read from a different .pdb fileprovided with -q. There is very little error
checking, so in this caseit is your responsibility to make sure all atoms in the structure fileand .pdb
file correspond exactly to each other.
Option -ox writes the B-factors to a file with the average coordinates in the trajectory.
With the option -od the root mean square deviation with respect to the reference structure is calculated.
With the option -aniso, gmx rmsf will compute anisotropic temperature factors and then it will also
output average coordinates and a .pdb file with ANISOU records (corresponding to the -oq or -ox option).
Please note that the U values are orientation-dependent, so before comparison with experimental data you
should verify that you fit to the experimental coordinates.
When a .pdb input file is passed to the program and the -aniso flag is set a correlation plot of the Uij
will be created, if any anisotropic temperature factors are present in the .pdb file.
With option -dir the average MSF (3x3) matrix is diagonalized. This shows the directions in which the
atoms fluctuate the most and the least.
OPTIONS
Options to specify input files:
-f [<.xtc/.trr/...>] (traj.xtc)
Trajectory: xtc trr cpt gro g96 pdb tng
-s [<.tpr/.gro/...>] (topol.tpr)
Structure+mass(db): tpr gro g96 pdb brk ent
-n [<.ndx>] (index.ndx) (Optional)
Index file
-q [<.pdb>] (eiwit.pdb) (Optional)
Protein data bank file
Options to specify output files:
-oq [<.pdb>] (bfac.pdb) (Optional)
Protein data bank file
-ox [<.pdb>] (xaver.pdb) (Optional)
Protein data bank file
-o [<.xvg>] (rmsf.xvg)
xvgr/xmgr file
-od [<.xvg>] (rmsdev.xvg) (Optional)
xvgr/xmgr file
-oc [<.xvg>] (correl.xvg) (Optional)
xvgr/xmgr file
-dir [<.log>] (rmsf.log) (Optional)
Log file
Other options:
-b <time> (0)
Time of first frame to read from trajectory (default unit ps)
-e <time> (0)
Time of last frame to read from trajectory (default unit ps)
-dt <time> (0)
Only use frame when t MOD dt = first time (default unit ps)
-[no]w (no)
View output .xvg, .xpm, .eps and .pdb files
-xvg <enum> (xmgrace)
xvg plot formatting: xmgrace, xmgr, none
-[no]res (no)
Calculate averages for each residue
-[no]aniso (no)
Compute anisotropic temperature factors
-[no]fit (yes)
Do a least squares superposition before computing RMSF. Without this you must make sure that the
reference structure and the trajectory match.
SEE ALSO
gmx(1)
More information about GROMACS is available at <http://www.gromacs.org/>.
COPYRIGHT
2025, GROMACS development team
2025.2 May 12, 2025 GMX-RMSF(1)