The Advent of Quantum Crystallography: Form and Structure Factors from Quantum Mechanics for Advanced Structure Refinement and Wavefunction Fitting

X-ray diffraction experiments contain much more information than the information usually exploited for structure determination. In quantum crystallography, quantum mechanical wavefunctions are used to extract that information about bonding and properties from the measured X-ray structure factors. Here we show how quantum mechanically derived structure factors and atomic form factors are constructed to allow the improved description of the diffraction experiment. Subsequently, we discuss the basics and the applications of the advanced structure refinement method Hirshfeld atom refinement and of the X-ray constrained wavefunction fitting technique.