g_spol(1) analyzes solvent dipole orientation and polarization around solutes


g_spol -f traj.xtc -s topol.tpr -n index.ndx -o scdist.xvg -[no]h -[no]version -nice int -b time -e time -dt time -[no]w -xvg enum -[no]com -refat int -rmin real -rmax real -dip real -bw real


g_spol analyzes dipoles around a solute; it is especially useful for polarizable water. A group of reference atoms, or a center of mass reference (option -com) and a group of solvent atoms is required. The program splits the group of solvent atoms into molecules. For each solvent molecule the distance to the closest atom in reference group or to the COM is determined. A cumulative distribution of these distances is plotted. For each distance between -rmin and -rmax the inner product of the distance vector and the dipole of the solvent molecule is determined. For solvent molecules with net charge (ions), the net charge of the ion is subtracted evenly from all atoms in the selection of each ion. The average of these dipole components is printed. The same is done for the polarization, where the average dipole is subtracted from the instantaneous dipole. The magnitude of the average dipole is set with the option -dip, the direction is defined by the vector from the first atom in the selected solvent group to the midpoint between the second and the third atom.


-f traj.xtc Input
 Trajectory: xtc trr trj gro g96 pdb cpt 

-s topol.tpr Input
 Run input file: tpr tpb tpa 

-n index.ndx Input, Opt.
 Index file 

-o scdist.xvg Output
 xvgr/xmgr file 


 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

 Use the center of mass as the reference postion

-refat int 1
 The reference atom of the solvent molecule

-rmin real 0
 Maximum distance (nm)

-rmax real 0.32
 Maximum distance (nm)

-dip real 0
 The average dipole (D)

-bw real 0.01
 The bin width