NAME
g_velacc - calculates velocity autocorrelation functions
VERSION 4.0.1
SYNOPSIS
g_velacc -f traj.trr -s topol.tpr -n index.ndx -o vac.xvg -[no]h -nice
int -b time -e time -dt time -[no]w -[no]xvgr -[no]m -[no]mol -acflen
int -[no]normalize -P enum -fitfn enum -ncskip int -beginfit real
-endfit real
DESCRIPTION
g_velacc computes the velocity autocorrelation function. When the -m
option is used, the momentum autocorrelation function is calculated.
With option -mol the velocity autocorrelation function of molecules is
calculated. In this case the index group should consist of molecule
numbers instead of atom numbers.
FILES
-f traj.trr Input
Full precision trajectory: trr trj cpt
-s topol.tpr Input, Opt.
Structure+mass(db): tpr tpb tpa gro g96 pdb
-n index.ndx Input, Opt.
Index file
-o vac.xvg Output
xvgr/xmgr file
OTHER OPTIONS
-[no]hno
Print help info and quit
-nice int 19
Set the nicelevel
-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 when t MOD dt = first time (ps)
-[no]wno
View output xvg, xpm, eps and pdb files
-[no]xvgryes
Add specific codes (legends etc.) in the output xvg files for the
xmgrace program
-[no]mno
Calculate the momentum autocorrelation function
-[no]molno
Calculate the velocity acf of molecules
-acflen int -1
Length of the ACF, default is half the number of frames
-[no]normalizeyes
Normalize ACF
-P enum 0
Order of Legendre polynomial for ACF (0 indicates none): 0, 1, 2 or
3
-fitfn enum none
Fit function: none, exp, aexp, exp_exp, vac, exp5, exp7 or
exp9
-ncskip int 0
Skip N points in the output file of correlation functions
-beginfit real 0
Time where to begin the exponential fit of the correlation function
-endfit real -1
Time where to end the exponential fit of the correlation function, -1
is till the end
SEE ALSO
gromacs(7)
More information about GROMACS is available at
<http://www.gromacs.org/>.
Thu 16 Oct 2008 g_velacc(1)