[Ifeffit] Fitting Commercial Molybdenum Disulfide
dmc at pdx.edu
dmc at pdx.edu
Fri Oct 29 10:24:32 CDT 2004
Mike & list,
Where can I find a reasonable model for my delr terms, if I do assume
that the bond angles are changing/there is no isotropic expansion? Is there a
description somewhere in the archives that I could look at?
Creating different sigma squared parameters for each path did help the R-
Factor somewhat, but not the reduced chi. Here's some data:
Fit with seperate sigma's:
Independent points = 14.312500000
Number of variables = 6.000000000
Chi-square = 5778.957783654
Reduced Chi-square = 695.212966455
R-factor = 0.029041008
Measurement uncertainty (k) = 0.000181935
Measurement uncertainty (R) = 0.004860095
Number of data sets = 1.000000000
Guess parameters +/- uncertainties (initial guess):
e0_1 = -4.0347670 +/- 2.9998980 (guessed as -4.072009
(1.919404))
ss = 0.0042860 +/- 0.0005990 (guessed as 0.004636
(0.000411))
e0 = 1.6770760 +/- 1.3230290 (guessed as 1.765958
(1.154388))
alpha = 0.0009180 +/- 0.0034050 (guessed as 0.001090
(0.002843))
ss2 = 0.0048160 +/- 0.0006910 (0.0000)
ss3 = 0.0225310 +/- 0.0657250 (0.0000)
Def parameters:
delr_1 = 0.0036440
Set parameters:
amp = 0.7
Correlations between variables:
e0_1 and alpha --> 0.8542
e0 and alpha --> 0.8470
e0_1 and e0 --> 0.7407
e0_1 and ss3 --> 0.7060
alpha and ss3 --> 0.4715
ss2 and ss3 --> -0.4214
e0_1 and ss2 --> -0.3892
e0 and ss3 --> 0.3772
alpha and ss2 --> -0.2680
All other correlations are below 0.25
Fit without (original):
Independent points = 14.312500000
Number of variables = 4.000000000
Chi-square = 6562.747150128
Reduced Chi-square = 636.387602437
R-factor = 0.032979787
Measurement uncertainty (k) = 0.000181935
Measurement uncertainty (R) = 0.004860095
Number of data sets = 1.000000000
Guess parameters +/- uncertainties (initial guess):
e0_1 = -4.0720130 +/- 1.9194050 (guessed as -4.072009
(1.919404))
ss = 0.0046360 +/- 0.0004110 (guessed as 0.004636
(0.000411))
e0 = 1.7659560 +/- 1.1543880 (guessed as 1.765958
(1.154388))
alpha = 0.0010900 +/- 0.0028430 (guessed as 0.001090
(0.002843))
Def parameters:
delr_1 = 0.0043250
Set parameters:
amp = 0.7
Correlations between variables:
e0_1 and alpha --> 0.8416
e0 and alpha --> 0.8045
e0_1 and e0 --> 0.7141
All other correlations are below 0.25
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