| VERSION 3.1 |
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.
option | filename | type | description |
---|---|---|---|
-f | traj.trr | Input | Full precision trajectory: trr trj |
-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 |
option | type | default | description |
---|---|---|---|
-[no]h | bool | no | Print help info and quit |
-[no]X | bool | no | Use dialog box GUI to edit command line options |
-nice | int | 19 | Set the nicelevel |
-b | time | -1 | First frame (ps) to read from trajectory |
-e | time | -1 | Last frame (ps) to read from trajectory |
-dt | time | -1 | Only use frame when t MOD dt = first time (ps) |
-[no]w | bool | no | View output xvg, xpm, eps and pdb files |
-[no]mol | bool | no | Calculate vac of molecules |
-acflen | int | -1 | Length of the ACF, default is half the number of frames |
-[no]normalize | bool | 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 or exp7 |
-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 |