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GMX-HBOND(1)			    GROMACS			  GMX-HBOND(1)

NAME
       gmx-hbond - Compute and analyze hydrogen	bonds.

SYNOPSIS
	  gmx hbond [-f	[<.xtc/.trr/...>]] [-s [<.tpr/.gro/...>]] [-n [<.ndx>]]
		    [-o	[<.ndx>]] [-num	[<.xvg>]] [-dist [<.xvg>]]
		    [-ang [<.xvg>]] [-dan [<.xvg>]] [-b	<time>]	[-e <time>]
		    [-dt <time>] [-tu <enum>] [-fgroup <selection>]
		    [-xvg <enum>] [-[no]rmpbc] [-[no]pbc] [-sf <file>]
		    [-selrpos <enum>] [-seltype	<enum>]	[-r <selection>]
		    [-t	<selection>] [-[no]m] [-[no]pf]	[-cutoff <real>]
		    [-hbr <real>] [-hba	<real>]	[-de <string>] [-ae <string>]

DESCRIPTION
       gmx hbond allows	using geometric	definition of hydrogen bonds to	define
       them throughout the structure.

       -r  specifies reference selection, relative to which the	search for hy-
       drogen bonds in target selection	will develop. Note that	all  atoms  in
       reference  and  target selections should	be either absolutely identical
       or non-overlapping at all. Accepts dynamic selection.

       -t specifies target selection, relative to which	the search for	hydro-
       gen  bonds  in reference	selection will develop.	Note that all atoms in
       reference and target selections should be either	 absolutely  identical
       or non-overlapping at all. Accepts dynamic selection.

       -m  forces to merge together information	in output index	file about hy-
       drogen bonds if they differ only	in hydrogen indices. This  also	 means
       that  information  about	hydrogen atoms in the hydrogen bonds would not
       be written in output index file at all.

       -pf forces to write hydrogen bonds for each frame separately instead of
       writing hydrogen	bonds for the whole system. Each information about hy-
       drogen bonds in new frame will be stored	in its own section of the out-
       put index file.

       -cutoff is a real value that defines distance from  donor  to  acceptor
       (and vice versa)	that used in neighbor search. Minimum (and also	recom-
       mended) value is	0.35.

       -hbr  Sets  the cutoff that is used when	calculating hydrogen bond dis-
       tances. Recommended value: 0.35.

       -hba Sets the cutoff that is used when calculating  hydrogen  bond  an-
       gles. Recommended value:	30.

       -de Specifies the atomic	elements that will be selected from the	topol-
       ogy to check if a given element is a potential hydrogen bond donor.

       -ae Specifies the atomic	elements that will be selected from the	topol-
       ogy to check if a given element is a potential hydrogen bond acceptor.

       -num  allows  you  to  get  a plot of the number	of hydrogen bonds as a
       function	of time	at the output.

       -dist allows you	to get a plot of the distance distribution of all  hy-
       drogen bonds at the output.

       -ang allows you to get a	plot of	the angular distribution of all	hydro-
       gen bonds at the	output.

       -dan  allows you	to get a plot of the number of analyzed	donors and ac-
       ceptors for each	frame at the output.

       Note that this is a new implementation of the hbond  utility  added  in
       GROMACS 2024. If	you need the old one, use gmx hbond-legacy.

OPTIONS
       Options to specify input	files:

       -f [<.xtc/.trr/...>] (traj.xtc) (Optional)
	      Input  trajectory	 or  single configuration: xtc trr cpt gro g96
	      pdb tng

       -s [<.tpr/.gro/...>] (topol.tpr)	(Optional)
	      Input structure: tpr gro g96 pdb brk ent

       -n [<.ndx>] (index.ndx) (Optional)
	      Extra index groups

       Options to specify output files:

       -o [<.ndx>] (hbond.ndx)
	      Index file that contains selected	groups',  acceptors',  donors'
	      and hydrogens' indices and hydrogen bond pairs between or	within
	      selected groups.

       -num [<.xvg>] (hbnum.xvg) (Optional)
	      Number of	hydrogen bonds as a function of	time.

       -dist [<.xvg>] (hbdist.xvg) (Optional)
	      Distance distribution of all hydrogen bonds.

       -ang [<.xvg>] (hbang.xvg) (Optional)
	      Angle distribution of all	hydrogen bonds.

       -dan [<.xvg>] (hbdan.xvg) (Optional)
	      Number of	donors and acceptors analyzed for each frame.

       Other options:

       -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 if	t MOD dt == first time (ps)

       -tu <enum> (ps)
	      Unit for time values: fs,	ps, ns,	us, ms,	s

       -fgroup <selection>
	      Atoms  stored in the trajectory file (if not set,	assume first N
	      atoms)

       -xvg <enum> (xmgrace)
	      Plot formatting: xmgrace,	xmgr, none

       -[no]rmpbc (yes)
	      Make molecules whole for each frame

       -[no]pbc	(yes)
	      Use periodic boundary conditions for distance calculation

       -sf <file>
	      Provide selections from files

       -selrpos	<enum> (atom)
	      Selection	reference positions: atom, res_com, res_cog,  mol_com,
	      mol_cog,	   whole_res_com,     whole_res_cog,	whole_mol_com,
	      whole_mol_cog,   part_res_com,	part_res_cog,	 part_mol_com,
	      part_mol_cog, dyn_res_com, dyn_res_cog, dyn_mol_com, dyn_mol_cog

       -seltype	<enum> (atom)
	      Default  selection  output  positions:  atom,  res_com, res_cog,
	      mol_com, mol_cog,	whole_res_com,	whole_res_cog,	whole_mol_com,
	      whole_mol_cog,	part_res_com,	 part_res_cog,	 part_mol_com,
	      part_mol_cog, dyn_res_com, dyn_res_cog, dyn_mol_com, dyn_mol_cog

       -r <selection>
	      Reference	selection, relative to which the search	 for  hydrogen
	      bonds in target selection	will develop.

       -t <selection>
	      Target  selection,  relative  to	which  the search for hydrogen
	      bonds in reference selection will	develop.

       -[no]m (no)
	      Merge together information about hydrogen	bonds if  they	differ
	      only in hydrogen indices.

       -[no]pf (no)
	      Write  hydrogen bonds for	each frame separately instead of writ-
	      ing hydrogen bonds for the whole system.

       -cutoff <real> (0.35)
	      Distance from donor to acceptor (and vice	versa)	that  used  in
	      neighbor search (nm). Must be > 0.

       -hbr <real> (0.35)
	      Hydrogen	bond cutoff distance, between donor and	acceptor (nm).
	      The value	must not exceed	the neighbor search cutoff and must be
	      >	0.

       -hba <real> (30)
	      A-D-H hydrogen bond cutoff angle (degrees). Must be > 0.

       -de <string> (N O)
	      Donor elements. Default elements:	N, O.

       -ae <string> (N O)
	      Acceptor elements. Default elements: N, O.

SEE ALSO
       gmx(1)

       More    information    about    GROMACS	  is	available    at	    <-
       http://www.gromacs.org/>.

COPYRIGHT
       2025, GROMACS development team

2025.0				 Feb 10, 2025			  GMX-HBOND(1)

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