.TH g_order 1 "Mon 4 Apr 2011" "" "GROMACS suite, VERSION 4.5.4-dev-20110404-bc5695c"
.SH NAME
g_order - computes the order parameter per atom for carbon tails

.B VERSION 4.5.4-dev-20110404-bc5695c
.SH SYNOPSIS
\f3g_order\fP
.BI "\-f" " traj.xtc "
.BI "\-n" " index.ndx "
.BI "\-nr" " index.ndx "
.BI "\-s" " topol.tpr "
.BI "\-o" " order.xvg "
.BI "\-od" " deuter.xvg "
.BI "\-ob" " eiwit.pdb "
.BI "\-os" " sliced.xvg "
.BI "\-Sg" " sg\-ang.xvg "
.BI "\-Sk" " sk\-dist.xvg "
.BI "\-Sgsl" " sg\-ang\-slice.xvg "
.BI "\-Sksl" " sk\-dist\-slice.xvg "
.BI "\-[no]h" ""
.BI "\-[no]version" ""
.BI "\-nice" " int "
.BI "\-b" " time "
.BI "\-e" " time "
.BI "\-dt" " time "
.BI "\-[no]w" ""
.BI "\-xvg" " enum "
.BI "\-d" " enum "
.BI "\-sl" " int "
.BI "\-[no]szonly" ""
.BI "\-[no]unsat" ""
.BI "\-[no]permolecule" ""
.BI "\-[no]radial" ""
.BI "\-[no]calcdist" ""
.SH DESCRIPTION
\&Compute the order parameter per atom for carbon tails. For atom i the
\&vector i\-1, i+1 is used together with an axis. 
\&The index file should contain only the groups to be used for calculations,
\&with each group of equivalent carbons along the relevant acyl chain in its own
\&group. There should not be any generic groups (like System, Protein) in the index
\&file to avoid confusing the program (this is not relevant to tetrahedral order
\&parameters however, which only work for water anyway).


\&The program can also give all
\&diagonal elements of the order tensor and even calculate the deuterium
\&order parameter Scd (default). If the option \fB \-szonly\fR is given, only one
\&order tensor component (specified by the \fB \-d\fR option) is given and the
\&order parameter per slice is calculated as well. If \fB \-szonly\fR is not
\&selected, all diagonal elements and the deuterium order parameter is
\&given.

The tetrahedrality order parameters can be determined
\&around an atom. Both angle an distance order parameters are calculated. See
\&P.\-L. Chau and A.J. Hardwick, Mol. Phys., 93, (1998), 511\-518.
\&for more details.

\&
.SH FILES
.BI "\-f" " traj.xtc" 
.B Input
 Trajectory: xtc trr trj gro g96 pdb cpt 

.BI "\-n" " index.ndx" 
.B Input
 Index file 

.BI "\-nr" " index.ndx" 
.B Input
 Index file 

.BI "\-s" " topol.tpr" 
.B Input
 Run input file: tpr tpb tpa 

.BI "\-o" " order.xvg" 
.B Output
 xvgr/xmgr file 

.BI "\-od" " deuter.xvg" 
.B Output
 xvgr/xmgr file 

.BI "\-ob" " eiwit.pdb" 
.B Output
 Protein data bank file 

.BI "\-os" " sliced.xvg" 
.B Output
 xvgr/xmgr file 

.BI "\-Sg" " sg\-ang.xvg" 
.B Output, Opt.
 xvgr/xmgr file 

.BI "\-Sk" " sk\-dist.xvg" 
.B Output, Opt.
 xvgr/xmgr file 

.BI "\-Sgsl" " sg\-ang\-slice.xvg" 
.B Output, Opt.
 xvgr/xmgr file 

.BI "\-Sksl" " sk\-dist\-slice.xvg" 
.B Output, Opt.
 xvgr/xmgr file 

.SH OTHER OPTIONS
.BI "\-[no]h"  "no    "
 Print help info and quit

.BI "\-[no]version"  "no    "
 Print version info and quit

.BI "\-nice"  " int" " 19" 
 Set the nicelevel

.BI "\-b"  " time" " 0     " 
 First frame (ps) to read from trajectory

.BI "\-e"  " time" " 0     " 
 Last frame (ps) to read from trajectory

.BI "\-dt"  " time" " 0     " 
 Only use frame when t MOD dt = first time (ps)

.BI "\-[no]w"  "no    "
 View output \fB .xvg\fR, \fB .xpm\fR, \fB .eps\fR and \fB .pdb\fR files

.BI "\-xvg"  " enum" " xmgrace" 
 xvg plot formatting: \fB xmgrace\fR, \fB xmgr\fR or \fB none\fR

.BI "\-d"  " enum" " z" 
 Direction of the normal on the membrane: \fB z\fR, \fB x\fR or \fB y\fR

.BI "\-sl"  " int" " 1" 
 Calculate order parameter as function of box length, dividing the box in nr slices.

.BI "\-[no]szonly"  "no    "
 Only give Sz element of order tensor. (axis can be specified with \fB \-d\fR)

.BI "\-[no]unsat"  "no    "
 Calculate order parameters for unsaturated carbons. Note that this cannot be mixed with normal order parameters.

.BI "\-[no]permolecule"  "no    "
 Compute per\-molecule Scd order parameters

.BI "\-[no]radial"  "no    "
 Compute a radial membrane normal

.BI "\-[no]calcdist"  "no    "
 Compute distance from a reference (currently defined only for radial and permolecule)

.SH SEE ALSO
.BR gromacs(7)

More information about \fBGROMACS\fR is available at <\fIhttp://www.gromacs.org/\fR>.