Fast and Accurate Quantum Crystallography: From Small to Large, from Light to Heavy

The
coupling of the crystallographic refinement technique Hirshfeld
atom refinement (HAR) with the recently constructed libraries of extremely
localized molecular orbitals (ELMOs) gives rise to the new quantum-crystallographic
method HAR-ELMO. This method is significantly faster than HAR but
as accurate and precise, especially concerning the free refinement
of hydrogen atoms from X-ray diffraction data, so that the first fully
quantum-crystallographic refinement of a protein is presented here.
However, the promise of HAR-ELMO exceeds large molecules and protein
crystallography. In fact, it also renders possible electron-density
investigations of heavy elements in small molecules and facilitates
the detection and isolation of systematic errors from physical effects.