1 .TH g_dielectric 1 "Thu 16 Oct 2008"
3 g_dielectric - calculates frequency dependent dielectric constants
8 .BI "-f" " dipcorr.xvg "
32 .BI "-nsmooth" " int "
34 dielectric calculates frequency dependent dielectric constants
35 from the autocorrelation function of the total dipole moment in
36 your simulation. This ACF can be generated by g_dipoles.
37 For an estimate of the error you can run g_statistics on the
38 ACF, and use the output thus generated for this program.
39 The functional forms of the available functions are:
42 One parmeter : y = Exp[-a1 x]
43 Two parmeters : y = a2 Exp[-a1 x]
44 Three parmeter: y = a2 Exp[-a1 x] + (1 - a2) Exp[-a3 x]
45 Startvalues for the fit procedure can be given on the commandline.
46 It is also possible to fix parameters at their start value, use -fix
47 with the number of the parameter you want to fix.
51 Three output files are generated, the first contains the ACF,
52 an exponential fit to it with 1, 2 or 3 parameters, and the
53 numerical derivative of the combination data/fit.
54 The second file contains the real and imaginary parts of the
55 frequency-dependent dielectric constant, the last gives a plot
56 known as the Cole-Cole plot, in which the imaginary
57 component is plotted as a function of the real component.
58 For a pure exponential relaxation (Debye relaxation) the latter
59 plot should be one half of a circle
61 .BI "-f" " dipcorr.xvg"
79 Print help info and quit
81 .BI "-nice" " int" " 19"
84 .BI "-b" " time" " 0 "
85 First frame (ps) to read from trajectory
87 .BI "-e" " time" " 0 "
88 Last frame (ps) to read from trajectory
90 .BI "-dt" " time" " 0 "
91 Only use frame when t MOD dt = first time (ps)
94 View output xvg, xpm, eps and pdb files
96 .BI "-[no]xvgr" "yes "
97 Add specific codes (legends etc.) in the output xvg files for the xmgrace program
100 use fast fourier transform for correlation function
103 use first column as X axis rather than first data set
105 .BI "-eint" " real" " 5 "
106 Time were to end the integration of the data and start to use the fit
108 .BI "-bfit" " real" " 5 "
111 .BI "-efit" " real" " 500 "
114 .BI "-tail" " real" " 500 "
115 Length of function including data and tail from fit
117 .BI "-A" " real" " 0.5 "
118 Start value for fit parameter A
120 .BI "-tau1" " real" " 10 "
121 Start value for fit parameter tau1
123 .BI "-tau2" " real" " 1 "
124 Start value for fit parameter tau2
126 .BI "-eps0" " real" " 80 "
127 Epsilon 0 of your liquid
129 .BI "-epsRF" " real" " 78.5 "
130 Epsilon of the reaction field used in your simulation. A value of 0 means infinity.
132 .BI "-fix" " int" " 0"
133 Fix parameters at their start values, A (2), tau1 (1), or tau2 (4)
135 .BI "-ffn" " enum" " none"
154 .BI "-nsmooth" " int" " 3"
155 Number of points for smoothing