NAME

gmx-sorient - Analyze solvent orientation around solutes

SYNOPSIS

gmx sorient [-f [<.xtc/.trr/...>]] [-s [<.tpr/.gro/...>]] [-n [<.ndx>]]


            [-o [<.xvg>]] [-no [<.xvg>]] [-ro [<.xvg>]]


            [-co [<.xvg>]] [-rc [<.xvg>]] [-b <time>] [-e <time>]


            [-dt <time>] [-[no]w] [-xvg <enum>] [-[no]com] [-[no]v23]


            [-rmin <real>] [-rmax <real>] [-cbin <real>]


            [-rbin <real>] [-[no]pbc]

DESCRIPTION

gmx sorient analyzes solvent orientation around solutes. It calculates two angles between the vector from one or more reference positions to the first atom of each solvent molecule:

theta_1: the angle with the vector from the first atom of the solvent molecule to the midpoint between atoms 2 and 3.
theta_2: the angle with the normal of the solvent plane, defined by the same three atoms, or, when the option -v23 is set, the angle with the vector between atoms 2 and 3.

The reference can be a set of atoms or the center of mass of a set of atoms. The group of solvent atoms should consist of 3 atoms per solvent molecule. Only solvent molecules between -rmin and -rmax are considered for -o and -no each frame.

-o: distribution of cos(theta_1) for rmin<=r<=rmax.

-no: distribution of cos(theta_2) for rmin<=r<=rmax.

-ro: <cos(theta_1)> and <3cos(^2theta_2)-1> as a function of the distance.

-co: the sum over all solvent molecules within distance r of cos(theta_1) and 3cos(^2(theta_2)-1) as a function of r.

-rc: the distribution of the solvent molecules as a function of r

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

Options to specify output files:

-o [<.xvg>] (sori.xvg): xvgr/xmgr file
-no [<.xvg>] (snor.xvg): xvgr/xmgr file
-ro [<.xvg>] (sord.xvg): xvgr/xmgr file
-co [<.xvg>] (scum.xvg): xvgr/xmgr file
-rc [<.xvg>] (scount.xvg): xvgr/xmgr 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]com (no): Use the center of mass as the reference position
-[no]v23 (no): Use the vector between atoms 2 and 3
-rmin <real> (0): Minimum distance (nm)
-rmax <real> (0.5): Maximum distance (nm)
-cbin <real> (0.02): Binwidth for the cosine
-rbin <real> (0.02): Binwidth for r (nm)
-[no]pbc (no): Check PBC for the center of mass calculation. Only necessary when your reference group consists of several molecules.

COPYRIGHT

2025, GROMACS development team

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SYNOPSIS

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