1 .TH genion 1 "Mon 4 Apr 2011" "" "GROMACS suite, VERSION 4.5.4-dev-20110404-3c0e5ec"
3 genion - generates mono atomic ions on energetically favorable positions
5 .B VERSION 4.5.4-dev-20110404-3c0e5ec
8 .BI "\-s" " topol.tpr "
9 .BI "\-table" " table.xvg "
10 .BI "\-n" " index.ndx "
12 .BI "\-g" " genion.log "
13 .BI "\-pot" " pot.pdb "
14 .BI "\-p" " topol.top "
16 .BI "\-[no]version" ""
20 .BI "\-pname" " string "
23 .BI "\-nname" " string "
28 .BI "\-scale" " real "
30 .BI "\-[no]neutral" ""
32 \&\fB genion\fR replaces solvent molecules by monoatomic ions at
33 \&the position of the first atoms with the most favorable electrostatic
34 \&potential or at random. The potential is calculated on all atoms, using
35 \&normal GROMACS particle\-based methods (in contrast to other methods
36 \&based on solving the Poisson\-Boltzmann equation).
37 \&The potential is recalculated after every ion insertion.
38 \&If specified in the run input file, a reaction field, shift function
39 \&or user function can be used. For the user function a table file
40 \&can be specified with the option \fB \-table\fR.
41 \&The group of solvent molecules should be continuous and all molecules
42 \&should have the same number of atoms.
43 \&The user should add the ion molecules to the topology file or use
44 \&the \fB \-p\fR option to automatically modify the topology.
47 \&The ion molecule type, residue and atom names in all force fields
48 \&are the capitalized element names without sign. This molecule name
49 \&should be given with \fB \-pname\fR or \fB \-nname\fR, and the
50 \&\fB [molecules]\fR section of your topology updated accordingly,
51 \&either by hand or with \fB \-p\fR. Do not use an atom name instead!
54 Ions which can have multiple charge states get the multiplicity
55 \&added, without sign, for the uncommon states only.
58 \&With the option \fB \-pot\fR the potential can be written as B\-factors
59 \&in a \fB .pdb\fR file (for visualisation using e.g. Rasmol).
60 \&The unit of the potential is 1000 kJ/(mol e), the scaling be changed
61 \&with the \fB \-scale\fR option.
64 \&For larger ions, e.g. sulfate we recommended using \fB genbox\fR.
66 .BI "\-s" " topol.tpr"
68 Run input file: tpr tpb tpa
70 .BI "\-table" " table.xvg"
74 .BI "\-n" " index.ndx"
80 Structure file: gro g96 pdb etc.
82 .BI "\-g" " genion.log"
86 .BI "\-pot" " pot.pdb"
88 Protein data bank file
90 .BI "\-p" " topol.top"
96 Print help info and quit
98 .BI "\-[no]version" "no "
99 Print version info and quit
101 .BI "\-nice" " int" " 19"
104 .BI "\-xvg" " enum" " xmgrace"
105 xvg plot formatting: \fB xmgrace\fR, \fB xmgr\fR or \fB none\fR
107 .BI "\-np" " int" " 0"
108 Number of positive ions
110 .BI "\-pname" " string" " NA"
111 Name of the positive ion
113 .BI "\-pq" " int" " 1"
114 Charge of the positive ion
116 .BI "\-nn" " int" " 0"
117 Number of negative ions
119 .BI "\-nname" " string" " CL"
120 Name of the negative ion
122 .BI "\-nq" " int" " \-1"
123 Charge of the negative ion
125 .BI "\-rmin" " real" " 0.6 "
126 Minimum distance between ions
128 .BI "\-[no]random" "yes "
129 Use random placement of ions instead of based on potential. The rmin option should still work
131 .BI "\-seed" " int" " 1993"
132 Seed for random number generator
134 .BI "\-scale" " real" " 0.001 "
135 Scaling factor for the potential for \fB \-pot\fR
137 .BI "\-conc" " real" " 0 "
138 Specify salt concentration (mol/liter). This will add sufficient ions to reach up to the specified concentration as computed from the volume of the cell in the input \fB .tpr\fR file. Overrides the \fB \-np\fR and \fB \-nn\fR options.
140 .BI "\-[no]neutral" "no "
141 This option will add enough ions to neutralize the system. In combination with the concentration option a neutral system at a given salt concentration will be generated.
144 \- Calculation of the potential is not reliable, therefore the \fB \-random\fR option is now turned on by default.
146 \- If you specify a salt concentration existing ions are not taken into account. In effect you therefore specify the amount of salt to be added.
151 More information about \fBGROMACS\fR is available at <\fIhttp://www.gromacs.org/\fR>.