Man Linux: Main Page and Category List

NAME

       g_dielectric - calculates frequency dependent dielectric constants

       VERSION 4.0.1

SYNOPSIS

       g_dielectric -f dipcorr.xvg -d deriv.xvg -o epsw.xvg -c cole.xvg -[no]h
       -nice int -b time -e time -dt time -[no]w  -[no]xvgr  -[no]fft  -[no]x1
       -eint  real  -bfit  real -efit real -tail real -A real -tau1 real -tau2
       real -eps0 real -epsRF real -fix int -ffn enum -nsmooth int

DESCRIPTION

       dielectric calculates frequency dependent dielectric constants from the
       autocorrelation function of the total dipole moment in your simulation.
       This ACF can be generated by g_dipoles.  For an estimate of  the  error
       you  can run g_statistics on the ACF, and use the output thus generated
       for this program.  The functional forms of the available functions are:

       One  parmeter  : y = Exp[-a1 x] Two parmeters : y = a2 Exp[-a1 x] Three
       parmeter: y = a2 Exp[-a1 x] + (1 - a2) Exp[-a3 x] Startvalues  for  the
       fit  procedure can be given on the commandline.  It is also possible to
       fix parameters at their start value, use -fix with the  number  of  the
       parameter you want to fix.

       Three  output  files  are  generated,  the  first  contains the ACF, an
       exponential fit to it with 1, 2 or  3  parameters,  and  the  numerical
       derivative  of  the combination data/fit.  The second file contains the
       real  and  imaginary  parts  of  the   frequency-dependent   dielectric
       constant,  the  last gives a plot known as the Cole-Cole plot, in which
       the   imaginary  component  is  plotted  as  a  function  of  the  real
       component.   For  a  pure exponential relaxation (Debye relaxation) the
       latter plot should be one half of a circle

FILES

       -f dipcorr.xvg Input
        xvgr/xmgr file

       -d deriv.xvg Output
        xvgr/xmgr file

       -o epsw.xvg Output
        xvgr/xmgr file

       -c cole.xvg Output
        xvgr/xmgr file

OTHER OPTIONS

       -[no]hno
        Print help info and quit

       -nice int 19
        Set the nicelevel

       -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 when t MOD dt = first time (ps)

       -[no]wno
        View output xvg, xpm, eps and pdb files

       -[no]xvgryes
        Add specific codes (legends etc.) in the  output  xvg  files  for  the
       xmgrace program

       -[no]fftno
        use fast fourier transform for correlation function

       -[no]x1yes
        use first column as X axis rather than first data set

       -eint real 5
        Time were to end the integration of the data and start to use the fit

       -bfit real 5
        Begin time of fit

       -efit real 500
        End time of fit

       -tail real 500
        Length of function including data and tail from fit

       -A real 0.5
        Start value for fit parameter A

       -tau1 real 10
        Start value for fit parameter tau1

       -tau2 real 1
        Start value for fit parameter tau2

       -eps0 real 80
        Epsilon 0 of your liquid

       -epsRF real 78.5
        Epsilon  of  the  reaction field used in your simulation. A value of 0
       means infinity.

       -fix int 0
        Fix parameters at their start values, A (2), tau1 (1), or tau2 (4)

       -ffn enum none
        Fit function:  none,  exp,  aexp,   exp_exp,   vac,   exp5,   exp7  or
       exp9

       -nsmooth int 3
        Number of points for smoothing

SEE ALSO

       gromacs(7)

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

                                Thu 16 Oct 2008                g_dielectric(1)