Liquiddiffract

Major Changes

- Gaussian fitting toolbox
The calculation of the x-ray weighting factors for partial pair correlations used by the curve-fitting toolbox has been altered slightly. The default behaviour is now to calculate the WKM approximation for the effective atomic number of each species, _K_p,_ at _Q=0_. The previous behaviour of calculating the average _K_p_ across the whole _Q_-range of the data is still available by selecting the option in the _Additional Preferences_ dialog. However, this option may lead to unphysical results for some sample if the _Q_-range is >~10, as the x-ray weights are affected by the _Q_-range.

Minor Changes

- Fixed a bug in the gaussian fitting toolbox where the plot view reset when the first peak was added

Major Changes

- The _Structural Information_ Tab
This new tab provides functionality to extract information on average bond lengths and coordination number from the calculated _RDF(r)_ and/or _T(r)_ functions.

There are two toolboxes provided:
- An _Integration Toolbox_: Integrate over the first peak in the _RDF(r)_ or _T(r)_ to estimate the bond-length and average coordination number of the first coordination shell for monatomic samples. Three different methods of calculating the coordination number are provided. The limits can be set manually, but there is also an auto-find feature to automatically refine the integration limits using optimisation/root-finding routines.
- A _Curve-fitting Toolbox_: Fit an arbitrary number of gaussian-type peaks to the _RDF(r)_ or _T(r)_ to estimate bond lengths and coordination numbers of correlated atomic pairs in polyatomic samples. X-ray weighting factors are applied automatically and the bond length and coordination number are actual fitting parameters. Any combination of individual peaks or parameters can be fixed or refined during the fit. There is also an optional skewness parameter to fit a skew-normal distribution that can be toggled for any peak.

- Fixed several bugs in the calculation of the S(Q) and g(r) for polyatomic samples

- LiquidDiffract is now distributed on PyPI

Minor Changes

- Added an option to calculate PDF functions directly without refining the _g(r)_ / _S(Q)_
- Added an option to load data in nm^-1
- Added an option to plot re-scaled Ashcroft-Langreth functions
- Added an option to use a modification function in the iterative refinement procedure
- Added a button to copy the refined value of ρ to the inital value input
- Faber-Ziman formalism is now the default
- The composition table is now scroll-able and easier to use
- Fixed several minor bugs in the GUI
- Fixed several Qt garbage collection errors when running LiquidDiffract on Windows
- Simplified the iterative refinement procedure in the code
- Changed references to the differential correlation function from _F(r)_ to _D(r)_ to be more consistent with the literature
- Updated the documentation