NAME¶

g_velacc - calculates velocity autocorrelation functions VERSION 4.5.4-dev-20110404-bc5695c

SYNOPSIS¶

g_velacc -f traj.trr -s topol.tpr -n index.ndx -o vac.xvg -[no]h -[no]version -nice int -b time -e time -dt time -[no]w -xvg enum -[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 -[no]versionno
Print version 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 -xvg enum xmgrace
xvg plot formatting: xmgrace, xmgr or none -[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, exp9 or erffit -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 until the end

SEE ALSO¶

gromacs(7) More information about GROMACS is available at <http://www.gromacs.org/>.