Mathematical tools to describe coherently crystalline matter and relevant properties, including presence of symmetry, mainly from a conceptual point of view but also supported by a basic vector analysis. The concept of Convolution in Chemistry and Physics. Being able to describe periodical phenomena, such as the electron density, in terms of an array of atoms and/or molecules via the trigonometric functions (Fourier analysis and transforms). Acquiring familiarity with the phenomena observed directly and their representation in the reciprocal point of view.
The existence of Fourier Transforms relations not only in diffraction theory but also in Spectroscopy.