man g_dielectric (Commandes) - g_dielectric VERSION 3.3_beta_20050823
NAME
g_dielectric VERSION 3.3_beta_20050823
SYNOPSIS
g_dielectric -f Mtot.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 Mtot.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]h no 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]w no View output xvg, xpm, eps and pdb files
-[no]xvgr yes Add specific codes (legends etc.) in the output xvg files for the xmgrace program
-[no]fft no use fast fourier transform for correlation function
-[no]x1 yes 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