Man page - gmx-sham(1)

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Manual

GMX-SHAM

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
SEE ALSO
COPYRIGHT

NAME

gmx-sham - Compute free energies or other histograms from histograms

SYNOPSIS

gmx sham [ -f [<.xvg>] ] [ -ge [<.xvg>] ] [ -ene [<.xvg>] ] [ -dist [<.xvg>] ]
[ -histo [<.xvg>] ] [ -bin [<.ndx>] ] [ -lp [<.xpm>] ]
[ -ls [<.xpm>] ] [ -lsh [<.xpm>] ] [ -lss [<.xpm>] ]
[ -ls3 [<.pdb>] ] [ -g [<.log>] ] [ -[no]w ] [ -xvg <enum> ]
[ -[no]time ] [ -b <real> ] [ -e <real> ] [ -ttol <real> ]
[ -n <int> ] [ -[no]d ] [ -[no]sham ] [ -tsham <real> ]
[ -pmin <real> ] [ -dim <vector> ] [ -ngrid <vector> ]
[ -xmin <vector> ] [ -xmax <vector> ] [ -pmax <real> ]
[ -gmax <real> ] [ -emin <real> ] [ -emax <real> ]
[ -nlevels <int> ]

DESCRIPTION

gmx sham makes multi-dimensional free-energy, enthalpy and entropy plots. gmx sham reads one or more .xvg files and analyzes data sets. The basic purpose of gmx sham is to plot Gibbs free energy landscapes (option -ls ) by Bolzmann inverting multi-dimensional histograms (option -lp ), but it can also make enthalpy (option -lsh ) and entropy (option -lss ) plots. The histograms can be made for any quantities the user supplies. A line in the input file may start with a time (see option -time ) and any number of y -values may follow. Multiple sets can also be read when they are separated by & (option -n ), in this case only one y -value is read from each line. All lines starting with # and @ are skipped.

Option -ge can be used to supply a file with free energies when the ensemble is not a Boltzmann ensemble, but needs to be biased by this free energy. One free energy value is required for each (multi-dimensional) data point in the -f input.

Option -ene can be used to supply a file with energies. These energies are used as a weighting function in the single histogram analysis method by Kumar et al. When temperatures are supplied (as a second column in the file), an experimental weighting scheme is applied. In addition the vales are used for making enthalpy and entropy plots.

With option -dim , dimensions can be gives for distances. When a distance is 2- or 3-dimensional, the circumference or surface sampled by two particles increases with increasing distance. Depending on what one would like to show, one can choose to correct the histogram and free-energy for this volume effect. The probability is normalized by r and rˆ2 for dimensions of 2 and 3, respectively. A value of -1 is used to indicate an angle in degrees between two vectors: a sin(angle) normalization will be applied. Note that for angles between vectors the inner-product or cosine is the natural quantity to use, as it will produce bins of the same volume.

OPTIONS

Options to specify input files:
-f [<.xvg>] (graph.xvg)

xvgr/xmgr file

-ge [<.xvg>] (gibbs.xvg) (Optional)

xvgr/xmgr file

-ene [<.xvg>] (esham.xvg) (Optional)

xvgr/xmgr file

Options to specify output files:
-dist [<.xvg>] (ener.xvg) (Optional)

xvgr/xmgr file

-histo [<.xvg>] (edist.xvg) (Optional)

xvgr/xmgr file

-bin [<.ndx>] (bindex.ndx) (Optional)

Index file

-lp [<.xpm>] (prob.xpm) (Optional)

X PixMap compatible matrix file

-ls [<.xpm>] (gibbs.xpm) (Optional)

X PixMap compatible matrix file

-lsh [<.xpm>] (enthalpy.xpm) (Optional)

X PixMap compatible matrix file

-lss [<.xpm>] (entropy.xpm) (Optional)

X PixMap compatible matrix file

-ls3 [<.pdb>] (gibbs3.pdb) (Optional)

Protein data bank file

-g [<.log>] (shamlog.log) (Optional)

Log file

Other options:
-[no]w (no)

View output .xvg , .xpm , .eps and .pdb files

-xvg <enum> (xmgrace)

xvg plot formatting: xmgrace, xmgr, none

-[no]time (yes)

Expect a time in the input

-b <real> (-1)

First time to read from set

-e <real> (-1)

Last time to read from set

-ttol <real> (0)

Tolerance on time in appropriate units (usually ps)

-n <int> (1)

Read this number of sets separated by lines containing only an ampersand

-[no]d (no)

Use the derivative

-[no]sham (yes)

Turn off energy weighting even if energies are given

-tsham <real> (298.15)

Temperature for single histogram analysis

-pmin <real> (0)

Minimum probability. Anything lower than this will be set to zero

-dim <vector> (1 1 1)

Dimensions for distances, used for volume correction (max 3 values, dimensions > 3 will get the same value as the last)

-ngrid <vector> (32 32 32)

Number of bins for energy landscapes (max 3 values, dimensions > 3 will get the same value as the last)

-xmin <vector> (0 0 0)

Minimum for the axes in energy landscape (see above for > 3 dimensions)

-xmax <vector> (1 1 1)

Maximum for the axes in energy landscape (see above for > 3 dimensions)

-pmax <real> (0)

Maximum probability in output, default is calculate

-gmax <real> (0)

Maximum free energy in output, default is calculate

-emin <real> (0)

Minimum enthalpy in output, default is calculate

-emax <real> (0)

Maximum enthalpy in output, default is calculate

-nlevels <int> (25)

Number of levels for energy landscape

SEE ALSO

gmx(1)

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COPYRIGHT

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