Schrödinger equation is the basic equation of wave mechanics which, for systems not dependent on time, takes the form:
where Ψ is the wavefunction, V is the potential energy expressed as a function of the spatial coordinates, E its total energy, 2 is the Laplacian operator, h is Planck’s constant, and m is the mass.
The regular array of atoms in a crystal is a three-dimensional diffraction grating for short-wavelength waves such as X-rays. The atoms are arranged in planes with interplanar spacing d. Diffraction maxima occur in the incident direction of the wave, measured from the surface of a plane of atoms, and the wavelength λ of the radiation satisfy Braggs’s law:
Generalic, Eni. "Prostorno centrirana tetragonska rešetka." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
Glossary
Periodic Table