PDielec Version 8.1.1 - Powder and Single Crystal Infrared Calculations The Python package PDielec calculates the infrared and terahertz absorption characteristics of crystalline materials by post-processing the output of solid-state quantum mechanical and molecular mechanical calculations of the phonons or dielectric response of the crystalline material. For crystalline samples (thin films or thick slabs) the program use generalized transfer and scattering matrix approaches to calculate the transmission, absorption and reflection. For powdered systems, the package calculates the internal electric field arising from different particle morphologies and calculates the resulting shift in absorption frequency and intensity arising from the coupling between a phonon and the internal field. The theory of the approach for small crystallites is published in the Journal of Computational Chemistry, DOI: 10.1002/jcc.24344 . Changes in version 8.1.1 The documentation has been revamped. An API description is now generated from each class and routine. The examples of Jupyter notebooks has been added to. Static routines have been created in the FitterTab to allow their use in notebooks The UnitCell and SuperCell classes have been enhance to use a units specifier Added new routines to the Materials and DielectricFunction classes to allow sigmas, oscillator strengths and frequencies to be changed The write_cif() routine in UnitCell has been modified slightly to allow files to be written Update of setup.py to reflect deprecation of naming of sklearn Development of helper functions to aid future use of notebooks Changes in version 8.1.0 Modifications to the plotter tab to allow the use of wavelength and frequency units Redesign of the single crystal scenario tab. The new design means that scripts are not backwards compatible. The method of calculation for single crystals can now be 'Transfer matrix' or 'Scattering matrix' The default method is 'Scattering matrix' Other changes to the Single Crystal options: Thick slab is now an option for an individual layer and has been termed 'Incoherent (non-reflective)' Other incoherent options have been added for a layer, using either intensities or phase matching the pygtm module has been modified so that subclasses are used for coherent and incoherent layers and 'Transfer matrix' and 'Scattering matrix' classes are subclasses of the pygtm 'System' class removed the need to have specific super- and sub-strate entries in the singleCrystalTab superstrate is the top of the material list and substrate is at the bottom. the old 'Thick slab' option is still available if the dielectric layer is the last in the list of materials Updated the progress bar algorithms Fixed a bug in the specification of the support matrix for the powder case Fixed a bug in the reporting of absorptance, s- and p- were reported the wrong way round Fixed a bug in the powder scenario tab, the super- and sub-matrix dielectric functions, were not being set properly for frequency dependent permittivities Fixed a bug in the plotting tab when writing to the spread-sheet a scalar permittivity The option to use slicing has been removed The option to do partial incoherence has been removed from the GUI but left in the code There are compatibility issues with the previous version, so some scripts may not be compatible.