NAME

       g_dielectric - calculates frequency dependent dielectric constants

       VERSION 4.6.5

SYNOPSIS

       g_dielectric -f dipcorr.xvg -d deriv.xvg -o epsw.xvg -c cole.xvg -[no]h -[no]version -nice int -b time -e
       time -dt time -[no]w -xvg enum -[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

         g_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.   The  functional
       forms of the available functions are:

       One parameter:    y = exp(-a_1 x),

       Two parameters:   y = a_2 exp(-a_1 x),

       Three parameters: y = a_2 exp(-a_1 x) + (1 - a_2) exp(-a_3 x).

       Start  values  for  the  fit  procedure  can  be  given  on the command line.  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

       -[no]versionno
        Print version 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

       -xvg enum xmgrace
        xvg plot formatting:  xmgrace,  xmgr or  none

       -[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 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
        epsilon0 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,  exp9 or  erffit

       -nsmooth int 3
        Number of points for smoothing

SEE ALSO

       gromacs(7)

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

                                                 Mon 2 Dec 2013                                  g_dielectric(1)