sctpl - Calculate Radii of Gyration From Scattering Curves

Useage:

Run using the command:

sctpl

This will produce the following prompts, you should provide the inputs shown in italics. Individual values to input are surrounded by square braces. When multiple values are requires they can either be separated by a space on the same line or entered on separate lines. The meaning of the input values are explained in the Notes section.

Enter data type (model [m] or exptl [x]): [curve type]

Enter title of plot: [title]

Number of curves? [1] [no. curves]

Enter name of file containing data: [input file]

Smearing (y/n)? [smearing]

Type of plot: 0 Ln(IQQ) / QQ: Thickness RG 1 Ln(IQ) / QQ: Cross-sectional RG 2 Ln(I) / QQ: Overall RG; Guinier plot 3 Ln(I) / Q: Wide Angle 4 I / Q 5 IQ*Q / Q: Volume plot

Choose one of the above [3]: [plot type] Which Q range to plot (Q1, Q2; Q1 < Q2) [Q min] [Q max]

Which Q range to fit a line to (Q3, Q4; Q3 < Q4)? [fit min] [fit max]

Choose a plot style: Join the dots, no symbols [0]: Symbols only [1]: Dots and symbols [2]. [plot style]

Take your pick: 1) Get another; 2) Add another; 3) Change axes' ranges; 4) Start again; 5) Manual R-factor; 6) Auto R-factor; 7) Change a given plot's attributes; 8) Save selected plots as ASCII; 9) Screen dump; 10) Redisplay a given plot; 11) Remove a plot; 12) Quit: [menu choice]

Notes:

The original sctpl performed plotting, this is not a current feature but the options remain for compatibility with old scripts. Plotting and fitting can now be performed using sas_curve_analysis.py.

curve type = choose of model [m] or exptl [x] curve

title = title for plot

no. curves = number of curves to analyse

input file = path to input scattering curve (with $I$ and $Q$ columns).

smearing = should the curve be smeared

plot type = choice from 'Type of plot' menu shown above. This defines the radius of gyration type to be out put:

0 radius of gyration ($R_{g}$) 1 cross sectional $R_{g}$ (usually called $R_{xs1}$) 2 thickness $R_{g}$ (usually called $R_{xs2}$)

Q min = minimum Q value for plot

Q max = maximum Q value for plot

fit min = minimum Q value for fit

fit max = maximum Q value for fit

plot style = type of points used in plot

menu choice = choice from 'Take your pick' menu

Output:

sctpl produces a single output file in the current directory called 'Sctpl6_Summary'.

This has the following format:

*input file*,*calc type* ,*title*, *fit Q range*, *fit points*, *result*, *result error*,*I0*, *I0 error*

calc type = + RG = radius of gyration ($R_{g}$) + RXS = cross sectional $R_{g}$ (usually called $R_{xs1}$) + RTH = thickness $R_{g}$ (usually called $R_{xs2}$)

fit Q range = Q min -> Q max

fit points = points on teh input curve that correspond to fit Q range

result = result of the radius of gyration calculation in the units of the inverse of the input Q values

result err = uncertainty in the result from curve fitting

I0 = extrapolated $I_{0}$ value

I0 error = uncertainty in the $I_{0}$ value from curve fitting