g_velacc(1)
NAME
g_velacc - calculates velocity autocorrelation functions
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]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 -s
option is used, the momentum autocorrelation function is calculated.
With option -mol the momentum 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
- -s topol.tpr Input, Opt.
- Structure+mass(db): tpr tpb tpa gro g96 pdb xml
- -n index.ndx Input, Opt.
- Index file
- -o vac.xvg Output
- xvgr/xmgr file
OTHER OPTIONS
- -[no]h no
- 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]w no
- View output xvg, xpm, eps and pdb files
- -[no]xvgr yes
- Add specific codes (legends etc.) in the output xvg files for the
- xmgrace program
- -[no]mol no
- Calculate vac of molecules
- -acflen int -1
- Length of the ACF, default is half the number of frames
- -[no]normalize yes
- 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
- More information about the GROMACS suite is available in /usr/share/doc/gromacs or at <http://www.gromacs.org/>.