[Ifeffit] problem of overestimated E0 (Edge-energy)

[JeongEunSuk]

Hello all
I want to understand EO(edge-energy), precisely. (In Artemis, EO is writed as Enor)
Generally, EO is energy when electrons start to go out from core atom in XAFS. 
As you know, the experiments show that to find EO is not easy in XAFS. 
To remove background, sometimes I chose EO, the value of the maximum derivative in Athena. 
and when fitting, the E0 is correted by theoritical FEFF. 
This is my question.
The attached file is the figure of Pt foil(Pt L3 edge measurement). 
I think edge-enegy has to be in range between A and C because electrons start to move to continum state in that range.
However, fitted E0 is shifted to C (about 11573eV). and then when removing background I chose E0=11563eV(This is Pt L3 edge).
Fitted E0 is overestimated value, compared with whit line(B).
That means the calculated EO obtained from FEFF8.0 (using auto-self consistency field potential) is larger than that of experiment. 
 Do I need to change SCF potential in FEFF8.0?
 
 
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This is fitting parameters and results(in my case, I used Linux version)
 
To remove background
    k -range = 2.5 ~ 15,   EO=11563eV, Rbkg=1.3, kweight =1
 
To fit data
 
k -range = 3.0~13.5,  R -range =2.3~13.5
 
1. fitting parameters
 
  set     macc = 0.0
  set     so2 = 0.89    // reduction factor
  guess   ePt = 0.0   // energy shift
  set   npt1=1.0                // the number of Pt (1.0  means 12  Pt atoms around core Pt)
 guess    dpt1 = 0.0042     // effective bonding length
 guess    sigpt1=0.005100   //Debye waller factor
 
2. fitting results
  fit results, goodness of fit, and error analysis:
     independent points in data    =       8.152
     number of variables in fit    =       3
     degrees of freedom in fit     =       5.152
     r-factor of fit               =       0.002700
     chi-square                    =    1267.097168
     reduced chi-square            =     245.926361
     feffit found the following values for the variables:
        variable            best fit value    uncertainty  initial guess
       ept            =       10.758198        0.860494        4.000000
       dpt1           =        0.006462        0.002930        0.004200
       sigpt1         =        0.005114        0.000098        0.005100
     correlation between variables
       variable #1    variable #2         correlation
       ept            dpt1                   0.926524
     all other correlations are less than    0.25000
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 Because the correlation between E0 and effective bonding length is big, I checked the fit as set bonding and the rest of parameters is variables,  and then the result is not changed. That means EO still is big.
 

 
 		 	   		  
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