EVAL15: a diffraction data integration method based onab initiopredicted profiles

Abstract

A novel diffraction data integration method is presented, EVAL15, based upon ab initio calculation of three‐dimensional (x, y, ω) reflection profiles from a few physical crystal and instrument parameters. Net intensities are obtained by least‐squares fitting the observed profile with the calculated standard using singular value decomposition. This paper shows that profiles can be predicted satisfactorily and that accurate intensities are obtained. The detailed profile analysis has the additional advantage that specific physical properties of the crystal are revealed. The EVAL15 method is particularly useful in circumstances where other programs fail, such as regions of reciprocal space with weak scattering, crystals with anisotropic shape or anisotropic mosaicity, Kα1/Kα2 peak splitting, interference from close neighbours, twin lattices, or satellite reflections of modulated structures, all of which may frustrate the customary profile learning and fitting procedures. EVAL15 allows the deconvolution of overlapping reflections.

DIALS: implementation and evaluation of a new integration package

“…The overwhelming majority of diffraction data resulting in PDB depositions over the last 2-3 decades have been analysed using just four programs: XDS (Kabsch, 2010b), MOSFLM (Leslie, 2006), HKL-2000/DENZO (Otwinowski & Minor, 1997) and d*TREK (Pflugrath, 1999). For chemical crystallography, SAINT (Bruker AXS Inc., Madison, Wisconsin, USA) and EVAL (Duisenberg et al, 2003;Schreurs et al, 2010) as well as d*TREK are in common use. Significant effort by a relatively small number of developers over this time has been critical to producing the diffraction-intensity data sets that are the raw material of structure determination.…”

New methods for indexing multi-lattice diffraction data

“…A more advanced approach would require the modification of integration software such that it is aware of the presence of multiple lattices, enabling the exclusion from background determination and profile fitting of pixels belonging to overlapping reflections (Fry et al, 1993). Alternatively, peak deconvolution procedures during integration such as those described by Bourgeois et al (1998) or Schreurs et al (2010) may work well in such cases. 4.1.2.…”

Multigrain crystallography

“…One solution may be to take an independent set of data with the detector positioned further away from the sample. Other solutions may be to generalize existing methods for integration based on peak profiles (Kabsch, 1988;Leslie, 1992;Otwinowski and Minor, 1997;Schreurs et al, 2010).…”