genion(1)

NAME
genion - generates mono atomic ions on energetically favorable positions VERSION 4.6.3

SYNOPSIS
genion -s topol.tpr -n index.ndx -o out.gro -p topol.top -[no]h -[no]version -nice int -np int -pname string -pq int -nn int -nname string -nq int -rmin real -seed int -conc real -[no]neutral

DESCRIPTION
genion randomly replaces solvent molecules with monoatomic ions. The group of solvent molecules should be continuous and all molecules should have the same number of atoms. The user should add the ion molecules to the topology file or use the -p option to automatically modify the topology. The ion molecule type, residue and atom names in all force fields are the capitalized element names without sign. This molecule name should be given with -pname or -nname, and the [molecules] section of your topology updated accordingly, either by hand or with -p. Do not use an atom name instead! Ions which can have multiple charge states get the multiplicity added, without sign, for the uncommon states only. For larger ions, e.g. sulfate we recommended using genbox.

FILES
-s topol.tpr Input
 Run input file: tpr tpb tpa -n index.ndx Input, Opt.
 Index file -o out.gro Output
 Structure file: gro g96 pdb etc. -p topol.top In/Out, Opt.
 Topology file

OTHER OPTIONS
-[no]hno
 Print help info and quit -[no]versionno
 Print version info and quit -nice int 19
 Set the nicelevel -np int 0
 Number of positive ions -pname string NA
 Name of the positive ion -pq int 1
 Charge of the positive ion -nn int 0
 Number of negative ions -nname string CL
 Name of the negative ion -nq int -1
 Charge of the negative ion -rmin real 0.6
 Minimum distance between ions -seed int 1993
 Seed for random number generator -conc real 0
 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 .tpr file. Overrides the -np and -nn options. -[no]neutralno
 This option will add enough ions to neutralize the system. These ions are added on top of those specified with -np/ -nn or -conc.

KNOWN PROBLEMS
- 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.

SEE ALSO
gromacs(7) More information about GROMACS is available at <http://www.gromacs.org/>.