SYNOPSISg_potential -f traj.xtc -n index.ndx -s topol.tpr -o potential.xvg -oc charge.xvg -of field.xvg -[no]h -[no]version -nice int -b time -e time -dt time -[no]w -xvg enum -d string -sl int -cb int -ce int -tz real -[no]spherical -ng int -[no]correct
DESCRIPTIONg_potential computes the electrostatical potential across the box. The potential is calculated by first summing the charges per slice and then integrating twice of this charge distribution. Periodic boundaries are not taken into account. Reference of potential is taken to be the left side of the box. It is also possible to calculate the potential in spherical coordinates as function of r by calculating a charge distribution in spherical slices and twice integrating them. epsilon_r is taken as 1, but 2 is more appropriate in many cases.
FILES-f traj.xtc Input
Trajectory: xtc trr trj gro g96 pdb cpt
Run input file: tpr tpb tpa
Print help info and quit
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)
View output .xvg, .xpm, .eps and .pdb files
-xvg enum xmgrace
xvg plot formatting: xmgrace, xmgr or none
-d string Z
Take the normal on the membrane in direction X, Y or Z.
-sl int 10
Calculate potential as function of boxlength, dividing the box in nr slices.
-cb int 0
Discard first nr slices of box for integration
-ce int 0
Discard last nr slices of box for integration
-tz real 0
Translate all coordinates distance in the direction of the box
Calculate spherical thingie
-ng int 1
Number of groups to consider
Assume net zero charge of groups to improve accuracy
KNOWN PROBLEMS- Discarding slices for integration should not be necessary.