TDFw Manual

The program has a menu, speed buttons and four tabs.

Buttons

Button	Action
	creates a default data template
	loads selected data file
	writes current data (including fitting results) into a file
	prints a hard copy of the data
	font selection
	prints the fitting curves
	checks data validity
	initial calculation
	single fitting iteration
	multiple iterations  *)
	help

^*) Multiple iterations - uses values from the Results Tab: Stops if number of iterations exceeds IterMax, the mean square deviation becomes less then dPPM, or energy step becomes smaller than dEmin

 This bar also contains the One-level Fit checkbox - Curie fit if checked, Two-level fit if unchecked.

Info tab

This tab contains the program title and contact information.  

Input tab

The experimental data can be loaded from a file or entered manually.

Loading data from file

To load data go to "File", "Open" and select a file. The standard extension is *.tdf. Actually the TDF-files are plain text files and can be created or modified using any text processor. The file structure is described below. The contents of the input file are displayed in the "Input" tab.

Manual input

The "Input" tab can be also used for manual input. 

• The upper edit box, Comment, contains identification text.
• Change the Number of NMR Lines and Number of Temperature Points from their defaults to the actual values. 
• Initial Energy Gap - starting value for iterations.
• Initial Delta E - step for changing the energy gap. The step decreases during iterations.
• 1st Level Spin - the ground state electronic spin. 
• 2nd Level Spin - the excited state electronic spin. 
• Use the Copy Spin Factor button to copy predefined spin factors to the selected NMR line (the first line in the data grid)
• Data grid
  • The default line names can be changed by right-clicking on the title row.

    

     
  • Spin factor - the factors for calculating atomic spin densities from Curie factors.
  • Dia Shifts - diamagnetic NMR  shifts for each line.
  • Enter available line shift values for each temperature point. Non-numeric values are interpreted as absent values and are displayed as _***.
• Estimate Dia Shifts button is used for the linear estimation of diamagnetic shifts.

 N_Experim - N_Param: Data Redundancy is determined automatically in calculations (Must be > 0).

 Data exclusion

Sometimes it is necessary to remove the entire row or column in the data grid (usually due to the low accuracy of measurement). This can be done by Shift-clicking (rows) or Ctrl-clicking (columns). The excluded rows and columns are marked as "X":

The values are not actually deleted, they are just not used in the fitting procedure. They can be undeleted by Shift/Ctrl clicking again. In the above example the 3rd point and the line "b" are excluded. In the output file (see the section below) the deleted values are labeled with zero weights:

Weight factors:
         Line 1 Line 2 Line 3 Line 4
Point 1      1      0      1      1
Point 2      1      0      1      1
Point 3      1      0      1      1
Point 4      0      0      0      0
Point 5      1      0      1      1

Fitting tab

After loading data from a file or manually entering data it is recommended to check data validity by pressing

For the calculation of initial quantities press

After the initial calculation, the Fitting and Results tabs become available for editing.

After that the fitting can be performed in three ways:

1. Semi-automatic fitting  . One iteration is performed by pressing this button. The values of mean square (standard)  deviation, the energy gap and the energy step are displayed for controlling iterations.
2. Multiple iterations . This regime uses values from the Results Tab: Stops if the number of iterations exceeds IterMax, the mean square deviation becomes less then dPPM or energy step becomes smaller than dEmin.

   

3. Manual fit.
   • Check Use Scrollbar
   • Set lower and upper limits for the energy gap variation.
   • Set the number of points in the variation interval, which determines the energy variation step.
   • Use a scrollbar for changing the energies. 

   

   In the above example the energy step is (555.5 - 0.001)/100 = 5.55499 cm^-1.

Results tab

• IterMax, dPPM and dEmin - the control values used in multi iteration fitting.
• Final energy gap.
• MSD or standard deviation (average fitting accuracy).

• Axial Shifts: Axial part of dipolar shifts F_Axial.
• Rhombic Shifts: Rhombic part of dipolar shifts F_Rhomb - Experimental values are necessary for the estimation of spin densities. They are subtracted from the temperature dependence using the following formula:

  (F_Axial + F_Rhomb) T_Ref /T

• T_Ref:  Reference Temperature.
• Shift₁(T _ref ), Shift₂(T _ref ): total shifts at the reference temperature.
• Curie-Factor1: Ground-state Curie factors.
• Curie-Factor2: Excited-state Curie factors (Their values do not depend on dipolar shifts).
• Spin Dens.1: Ground-state calculated spin densities.
• Spin Dens.2: Excited-state calculated spin densities.
• Level Cond.: Conditions for each line ( see reference 1 ).
• CF_{2 min}, CF_{2 max}: Limits to restrict variation on the excited state Curie factors. They are used to suppress instabilities in solutions.

Recalculate: Calculations with new dipolar shifts.
 

Menu options

• File
  • New - creates new data with 4 temperature points and 1 line; the same as
  • Open - loads selected data file; the same as
  • Save - saves entered, edited and calculated data; the same as
  • Print
    • Print - prints a hard copy of data; the same as
    • Font -  font selection; the same as
    • Print fit - prints the fitting curves; the same as  
• Run
  • Check - checks data validity; the same as
  • Run - initial calculation; the same as .
• Help
  • Help; the same as  
  • About

File format

The input file is a simple Text (ASCII) file. Each line contains data and an optional comment string in the end (displayed in red). The same format is used for output files. Below is a sample file.

Sample file

2
1  1 = Calculated, 0 = Not calculated
Curie Dependence Sample File
4  - Number of Lines
5  - Number of Temperature points
  0.5
  0.5
               a     |    b     |    c     |    d
           -496.8000  -496.8000  -496.8000  -496.8000   - Spin Factors
              0.0000     0.0000     0.0000     0.0000   - Dia Shifts
    3.4000  -30.0000   -26.6000   -24.8000   -27.7000   - 1000/T, Para Shifts, Point   1
    3.5700  -31.4000   -28.0000   -25.8000   -29.3000   - 1000/T, Para Shifts, Point   2
    3.9200  -35.4000   -31.1000   -28.1000   -32.9000   - 1000/T, Para Shifts, Point   3
    4.3300  -39.6000   -34.1000   -30.0000   -36.7000   - 1000/T, Para Shifts, Point   4
    4.8200  -44.6000   -37.6000   -32.2000   -41.3000   - 1000/T, Para Shifts, Point   5

Description

1. Version (currently 2).
2. Calculation status: 1 = Calculated, 0 = Not calculated - distinguishes between the input and out files. The latter contain the fitting information at the end of the file. 
3. Comment.
4. Number of NMR lines.
5. Number of temperature points (Number of experiments).
6. Ground-state electronic spin. 
7. Excited-state electronic spin.
8. Line names separated by "|".
9. Spin factors.
10. Diamagnetic shifts (in this example diamagnetic shifts are already subtracted from all lines).
11. 1000/T, Paramagnetic Shifts (Lines 11 to 15).

Remark 1: All comments (displayed in red) are optional and can be omitted.

Remark 2: All values should be separated by at least one space.

Output file

The output files contains the input information in the beginning (this means that output files can be used as input files also). 

Next, the output file contains the data from the Results tab.

After that, the fitting curves are recorded (1000/T, Paramagnetic Shifts - 51 equidistant points). They can be used in plotting programs.

The weight matrix is recorded at the end of output files.

Weight matrix

The weight matrix is 1 if the point was used in fitting or 0 if it was excluded.

Weight factors:
         Line 1 Line 2 Line 3 Line 4
Point 1      1      1      0      1
Point 2      1      1      0      1
Point 3      1      1      1      1
Point 4      1      1      1      1
Point 5      1      1      1      1

 In the above example the first two points of the third line were excluded (or are missing).

Back to Temperature Dependence of NMR

©Nikolai V. Shokhirev, 2002-2004