# Research Focus

## 3D Electron Diffraction

3D Electron crystallography is a facinating extension to X-ray crystallography. Crystals smaller than the grains of icing sugar are big enough for single crystal structure determination. Electron crystallography has great potential in Chemical Crystallography.

The field is fast progressing, and this web site is difficult to keep up to date

## Single Crystal Neutron Diffraction

I spent some time looking into **single crystal neutron
diffraction**. SHELXL was modified to simplify refinement against neutron
data, in particular the handling of hydrogen (deuterium atoms) and their
restraints. See Gruene et
al, J. Appl. Cryst. (2014), Vol. 47, 462-466, DOI 10.1107/S1600576713027659

I have given several talks on neutron diffraction.

## Crystallography beyond automation

Other than neutron diffraction I am interested in crystallography where it
becomes *demanding*, as in the building and refinement of the yeast RNA polymerase I.See Fernández-Tornero *et
al.*, Nature (2013), Vol. 502, 644-649 and Moreno-Morcillo *et
al.*, Acta Crystallogr. (2014), D70, 2570-2572

The tool mrtailor is one result that came out of this project.

Another project in this direction is the Complete Cross-Validation in
Crystallography. R_{complete} is particularly interesting for
small molecule crystallography, where the absolute number of data (reflections)
is small. The bias-free model R-value equals the arithmetic mean between R1 and
R_{complete}, hence the gap between R1 and R_{complete} measures
the amount of overfitting against errors in the data.

# Research Projects

- Refinement against Neutron Data with shelxl
- Complete Cross-Validation in Crystallography
- Nucleic Acid Tracing
- MrTailor
- mtz2sca V0.3
- mtz2hkl V0.3

Last modified: Mar 25, 2020 22:48