gmx gangle¶
Synopsis¶
gmx gangle [-f [<.xtc/.trr/...>]] [-s [<.tpr/.gro/...>]] [-n [<.ndx>]] [-oav [<.xvg>]] [-oall [<.xvg>]] [-oh [<.xvg>]] [-b <time>] [-e <time>] [-dt <time>] [-tu <enum>] [-fgroup <selection>] [-xvg <enum>] [-[no]rmpbc] [-[no]pbc] [-sf <file>] [-selrpos <enum>] [-seltype <enum>] [-g1 <enum>] [-g2 <enum>] [-binw <real>] [-group1 <selection>] [-group2 <selection>]
Description¶
gmx gangle
computes different types of angles between vectors.
It supports both vectors defined by two positions and normals of
planes defined by three positions.
The z axis or the local normal of a sphere can also be used as
one of the vectors.
There are also convenience options ‘angle’ and ‘dihedral’ for
calculating bond angles and dihedrals defined by three/four
positions.
The type of the angle is specified with -g1
and -g2
.
If -g1
is angle
or dihedral
, -g2
should not be specified.
In this case, -group1
should specify one or more selections,
and each should contain triplets or quartets of positions that define
the angles to be calculated.
If -g1
is vector
or plane
, -group1
should specify selections that contain either pairs (vector
)
or triplets (plane
) of positions. For vectors, the positions
set the endpoints of the vector, and for planes, the three positions
are used to calculate the normal of the plane. In both cases,
-g2
specifies the other vector to use (see below).
With -g2 vector
or -g2 plane
, -group2
should
specify another set of vectors. -group1
and -group2
should specify the same number of selections. It is also allowed to
only have a single selection for one of the options, in which case
the same selection is used with each selection in the other group.
Similarly, for each selection in -group1
, the corresponding
selection in -group2
should specify the same number of
vectors or a single vector. In the latter case, the angle is
calculated between that single vector and each vector from the other
selection.
With -g2 sphnorm
, each selection in -group2
should
specify a single position that is the center of the sphere.
The second vector is calculated as the vector from the center to the
midpoint of the positions specified by -group1
.
With -g2 z
, -group2
is not necessary, and angles
between the first vectors and the positive Z axis are calculated.
With -g2 t0
, -group2
is not necessary, and angles
are calculated from the vectors as they are in the first frame.
There are three options for output:
-oav
writes an xvg file with the time and the average angle
for each frame.
-oall
writes all the individual angles.
-oh
writes a histogram of the angles. The bin width can be
set with -binw
.
For -oav
and -oh
, separate average/histogram is
computed for each selection in -group1
.
Options¶
Options to specify input files:
-f
[<.xtc/.trr/…>] (traj.xtc) (Optional)- Input trajectory or single configuration: xtc trr cpt gro g96 pdb tng
-s
[<.tpr/.gro/…>] (topol.tpr) (Optional)- Input structure: tpr gro g96 pdb brk ent
-n
[<.ndx>] (index.ndx) (Optional)- Extra index groups
Options to specify output files:
-oav
[<.xvg>] (angaver.xvg) (Optional)- Average angles as a function of time
-oall
[<.xvg>] (angles.xvg) (Optional)- All angles as a function of time
-oh
[<.xvg>] (anghist.xvg) (Optional)- Histogram of the angles
Other options:
-b
<time> (0)- First frame (ps) to read from trajectory
-e
<time> (0)- Last frame (ps) to read from trajectory
-dt
<time> (0)- Only use frame if t MOD dt == first time (ps)
-tu
<enum> (ps)- Unit for time values: fs, ps, ns, us, ms, s
-fgroup
<selection>- Atoms stored in the trajectory file (if not set, assume first N atoms)
-xvg
<enum> (xmgrace)- Plot formatting: none, xmgrace, xmgr
-[no]rmpbc
(yes)- Make molecules whole for each frame
-[no]pbc
(yes)- Use periodic boundary conditions for distance calculation
-sf
<file>- Provide selections from files
-selrpos
<enum> (atom)- Selection reference positions: atom, res_com, res_cog, mol_com, mol_cog, whole_res_com, whole_res_cog, whole_mol_com, whole_mol_cog, part_res_com, part_res_cog, part_mol_com, part_mol_cog, dyn_res_com, dyn_res_cog, dyn_mol_com, dyn_mol_cog
-seltype
<enum> (atom)- Default selection output positions: atom, res_com, res_cog, mol_com, mol_cog, whole_res_com, whole_res_cog, whole_mol_com, whole_mol_cog, part_res_com, part_res_cog, part_mol_com, part_mol_cog, dyn_res_com, dyn_res_cog, dyn_mol_com, dyn_mol_cog
-g1
<enum> (angle)- Type of analysis/first vector group: angle, dihedral, vector, plane
-g2
<enum> (none)- Type of second vector group: none, vector, plane, t0, z, sphnorm
-binw
<real> (1)- Binwidth for -oh in degrees
-group1
<selection>- First analysis/vector selection
-group2
<selection>- Second analysis/vector selection