You are invited to a series of 10 tuition-free, hour-and-a-half webinars on advanced topics in practical X-ray crystallography.

We will cover microED, Olex2, Twinning, the Cambridge Structural Database, powder data collection and processing, Pair Distribution Function (PDF), small angle X-ray scattering (SAXS), protein crystallography, non-spherical atom refinement with NoSpherA2 and charge density.

The series runs June 7–18, 2021 at 8:00 AM CDT every weekday. (Use this Time Zone converter to determine your local time.)

Paul Swepston Joseph Ferrara Fraser White
School Directors: Dr. Paul Swepston, Dr. Joseph Ferrara and Dr. Fraser White

Program

Lecturer: Mathias Meyer

Host: Joe Ferrara

Class description: Electron diffraction is known for a long time. Recently with use of vacuum flange HPAD detectors a sensitive and effective setup was found to push microED to the mainstream. This allows to get structural information from sub-micron samples in short wall clock time.

The talk will describe the instrumentation, the practical aspects of the experiment, the data reduction and the structure solution and refinement in kinematical approximation.

All this will be exemplified with Rigaku’s new electron diffractometer that was developed and build with JEOL. A new version of CrysAlisPro features new electron diffraction tools for experimenting and data reduction.

Lecturer: Horst Puschmann

Host: Joe Ferrara

Class description: We will solve and refine a simple structure using Olex2. We will move on to progressively more tricky cases in this short whirlwind tour of Olex2.

There will be many tips and tricks, and we will cover subjects including modelling of complex disorder, dealing with twinning and even venture into the exciting new waters of anharmonic refinement and the use of non-spherical form factors in the refinement of routine X-ray structures.

Lecturer: Fraser White

Host: Joe Ferrara

Class description: Twinning is a commonly encountered phenomenon in X-ray crystallography which can make life more difficult. It is highly likely that you will encounter twinning in your crystallographic career if you have not already. Modern software and better hardware have made treatment of twinning much more routine however understanding what twinning is and how it can be handled is still important knowledge for a crystallographer to ensure the best results can be achieved. This session will therefore explain the different types of twinning which can occur, their traits and thus how to identify them, and the circumstances under which they might arise. Following this, strategies for treating twinned samples, from data collection and processing through to structure solution and hrefinement will be discussed.

Lecturer: Jeff Lengyel

Host: Joe Ferrara

Class description: The Cambridge Crystallographic Data Centre (CCDC) hosts and curates the Cambridge Structural Database (CSD), the world's largest repository of small-molecule organic and metal-organic crystal structures. In this lecture, we will:

  • Demonstrate how to use this large data collection to compliment your crystallographic studies.
  • Explore ways to create highly customizable visualizations of crystal structures using the Mercury program.
  • Show how to submit your own crystal structures to the database for publication.

Lecturer: Pierre Le Maguerès

Host: Joe Ferrara

Class description: Rigaku single crystal X-ray diffractometers all come with CrysAlisPro, a user-inspired data collection and data processing software for small molecule and protein crystallography single crystals. However, CrysAlisPro also has a module allowing for the collection of powder data on single crystal diffractometers, using transmission method and samples mounted in a capillary … or within a loop.

The powder data collection class will cover the following topics:

  • How to best prepare powder samples in loops or capillaries for data collection on the XtaLAB Synergy-S single crystal diffractometer
  • How to collect data with CrysAlisPro, including Pair Distribution Function (PDF) data
  • How to apply baseline correction to the collected and have CrysAlisPro output the 2-D data I vs. 2theta into a format suitable for full analysis by 3rd party programs.

Lecturer: Simon Bates

Host: Joe Ferrara

Class description: Atomic pair distribution functions (PDFs) have a venerable history for material structure analysis and were first applied to X-ray diffraction analysis by Debye and Menke in the 1930s. An atomic pair distribution function as measured by X-ray diffraction is essentially a histogram of atom-atom distances weighted by the electron density at each atom and is an essential component of the Debye diffraction theory. You may wonder why any of that should be of interest to you. But it turns out that one of the best ways to collect X-ray data suitable for PDF determination is using a single crystal diffraction system, and there are many materials problems that can only be addressed by using PDF methods. In this session we will learn more about the elegant beauty of PDFs and the Debye diffraction theory, how we collect optimum data and the type of analysis that can be performed.

Lecturer: Mark Del Campo

Host: Joe Ferrara

Class description: Small angle X-ray scattering (SAXS) is used to analyze structural parameters of biological macromolecules in solution. In combination with other structural techniques, SAXS amplifies understanding of macromolecules in biologically relevant conditions. In this session, we will cover SAXS theory, instrumentation, sample considerations, making a SAXS measurement, and different types of analysis.

Lecturer: Mark Del Campo

Host: Joe Ferrara

Class description: This lecture will familiarize you with the practical aspects of working with macromolecular crystal samples. We will cover sample mounting and handling, approach to crystal screening, data collection strategy tips, processing data to the so called “resolution” limit, and the appropriate hreflection file format. In addition, we will recommend some programs for structure solution.

Lecturer: Florian Kleemis

Host: Joe Ferrara

Class description: Modern diffractometers routinely produce data of quality much higher than the common model used for hrefinement can explain. The residual densities observed are, however, not random. They do carry chemical and structural information. In this tutorial NoSpherA2 (Non-Spherical Atoms in Olex2) will be shown as a tool to obtain superior structural results from identical data only relying on a better model of the atomic shape. Using this technique, the routine refinement of Hydrogen Atom parameters becomes possible alongside improved uncertainties of all atom positions and displacement parameters. The control and interpretation of results from such refinements will be discussed and differences in comparison to spherical atom refinements highlighted.

Lecturer: Chris Schürmann

Host: Joe Ferrara

Class description: This lecture will focus on the theoretical and experimental aspects of experimental charge-density determination. We will discuss the underlying theory and practical application of different, contemporary approaches for building and refining charge-density models, as well as the analysis and interpretation of the refined density distribution. Some of the methods for refining the charge density require high-resolution and high-quality data, therefore the collection and processing of such data is an important topic. Finally, the assessment of model and data quality is imperative for a successful charge density determination. Therefore, this lecture will also include an introduction to some tools for model and data quality assessment.

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