1GMX-SPOL(1) GROMACS GMX-SPOL(1)
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6 gmx-spol - Analyze solvent dipole orientation and polarization around
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10 gmx spol [-f [<.xtc/.trr/...>]] [-s [<.tpr>]] [-n [<.ndx>]]
11 [-o [<.xvg>]] [-b <time>] [-e <time>] [-dt <time>] [-[no]w]
12 [-xvg <enum>] [-[no]com] [-refat <int>] [-rmin <real>]
13 [-rmax <real>] [-dip <real>] [-bw <real>]
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16 gmx spol analyzes dipoles around a solute; it is especially useful for
17 polarizable water. A group of reference atoms, or a center of mass ref‐
18 erence (option -com) and a group of solvent atoms is required. The pro‐
19 gram splits the group of solvent atoms into molecules. For each solvent
20 molecule the distance to the closest atom in reference group or to the
21 COM is determined. A cumulative distribution of these distances is
22 plotted. For each distance between -rmin and -rmax the inner product
23 of the distance vector and the dipole of the solvent molecule is deter‐
24 mined. For solvent molecules with net charge (ions), the net charge of
25 the ion is subtracted evenly from all atoms in the selection of each
26 ion. The average of these dipole components is printed. The same is
27 done for the polarization, where the average dipole is subtracted from
28 the instantaneous dipole. The magnitude of the average dipole is set
29 with the option -dip, the direction is defined by the vector from the
30 first atom in the selected solvent group to the midpoint between the
31 second and the third atom.
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34 Options to specify input files:
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36 -f [<.xtc/.trr/…>] (traj.xtc)
37 Trajectory: xtc trr cpt gro g96 pdb tng
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39 -s [<.tpr>] (topol.tpr)
40 Portable xdr run input file
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42 -n [<.ndx>] (index.ndx) (Optional)
43 Index file
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45 Options to specify output files:
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47 -o [<.xvg>] (scdist.xvg)
48 xvgr/xmgr file
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50 Other options:
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52 -b <time> (0)
53 Time of first frame to read from trajectory (default unit ps)
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55 -e <time> (0)
56 Time of last frame to read from trajectory (default unit ps)
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58 -dt <time> (0)
59 Only use frame when t MOD dt = first time (default unit ps)
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61 -[no]w (no)
62 View output .xvg, .xpm, .eps and .pdb files
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64 -xvg <enum> (xmgrace)
65 xvg plot formatting: xmgrace, xmgr, none
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67 -[no]com (no)
68 Use the center of mass as the reference position
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70 -refat <int> (1)
71 The reference atom of the solvent molecule
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73 -rmin <real> (0)
74 Maximum distance (nm)
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76 -rmax <real> (0.32)
77 Maximum distance (nm)
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79 -dip <real> (0)
80 The average dipole (D)
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82 -bw <real> (0.01)
83 The bin width
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86 gmx(1)
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88 More information about GROMACS is available at <‐
89 http://www.gromacs.org/>.
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92 2019, GROMACS development team
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972019.2 Apr 16, 2019 GMX-SPOL(1)