The development of multidetectors for use in X‐ray and neutron scattering experiments has created an interest in methods for integrating Bragg peaks in three‐dimensional data arrays representing intensity scattered from single crystals. A method of using a priori information, extracted from the strongest peaks, to obtain statistically optimum results has been developed at the Institut Laue–Langevin (ILL), Grenoble. The method is outlined in this paper and results of its application to neutron diffraction are discussed.

LA UEGEN version 6.0 is a significantly developed version of the original LAUEGEN program [Campbell (1995a). J. Appl. Cryst. 28,[228][229][230][231][232][233][234][235][236]. It is an X-Windows-based program which now carries out the stages of processing Laue diffraction data up to and including the integration of spot intensities. The integration routines have also been incorporated in a standalone integration program INTLDM. The programs are distributed as part of the Daresbury Laboratory Laue Software Suite.

Neutron quasi-Laue diffraction data (2 A resolution) from tetragonal hen egg-white lysozyme were collected in ten days with neutron imaging plates. The data processing Laue software, LAUEGEN, developed for X-ray Laue diffractometry, was adapted for neutron diffractometry with a cylindrical detector. The data analysis software, X-PLOR, was modified and used for the refinement of hydrogen atoms, and the positions of 960 hydrogen atoms in the protein and 157 bound water molecules, were determined. Several examples are given of the methods used to identify hydrogen atoms and water molecules.

The correct positions of the deuterium (D) atoms of many of the bound waters in the protein concanavalin A are revealed by neutron Laue diffraction. The approach includes cases where these water D atoms show enough mobility to render them invisible even to ultra-high resolution synchrotronradiation X-ray crystallography. The positions of the bound water H atoms calculated on the basis of chemical and energetic considerations are often incorrect. The D-atom positions for the water molecules in the Mn-, Ca-and sugarbinding sites of concanavalin A are described in detail.

Triclinic crystals of lysozyme, hydrogen-deuterium exchanged in deuterated solvent, have been studied using neutron quasi-Laue techniques and a newly developed cylinder image-plate detector. The wavelength range employed was from 2.7 to 3.5 A, which gave 9426 significant reflections [F >/= 2sigma(F)] to a resolution limit of 1. 7 A. The deuteration states of the H atoms in the protein molecule were identified, followed by an extensive analysis of the water structure surrounding the protein. The final R factor was 20.4% (Rfree = 22.1%). In total, the 244 observed water molecules form approximately one layer of water around the protein with far fewer water molecules located further away. Water molecules covering the apolar patches make tangential layers at 4-5 A from the surface or form C-H...O contacts, and several water-molecule sites can be identified in the apolar cavities. Many of the water molecules are apparently orientationally disordered, and only 115 out of the 244 water molecules sit in mean single orientations. Comparison of these results with quasi-elastic neutron scattering observations of the water dynamics leads to a picture of the water molecules forming an extended constantly fluctuating network covering the protein surface.

Capper t u g d a t e become. antiterromagnetically ordered below 23.0(2) K and ibs magnetic structure has been determined I " singl-ystal unpolarized neutron diffraction measurements at 5 K. The chemical unit cell is triclinic Pi, with (L = 4.694(1), 6 = 5.830(1). c = 4.877(1) A, OT = 91.€4(1), @ = 92.41(2) and r = 82.91(1)o at 15 K. The magnetic propagation vector is ( $ 0 0 ) and the magnetic space group P 2 . i . The two equivalent copper ions within the unit cell have magnetic moments of 0.67(1) pg aligned ferromagnetically at the sphuiorl polar ang l s B = 121(2)O and d = 52(2)', the polar axis being parallel to e and Q being measured from the =-a* plane. This direaim coincides, within experimudal error, with the axis of elongation o f the Jahn-Teller distorted octahedmn of oxygen a t o m about the Cu't ion. A multipole refinement of the moment distribution, to order two on quantum u e s Z parallel to the moment direction and X , Y directed towards the four close oxygen neighbours, shows that Y20 is the only significant multipole.Its sign indicates that the moment distribution approximates to an oblate ellipsoid of revolution with its axis parallel to Z. Only two of the six oxygen neighbours of the Cuz+ ion carry a significant transferred moment of 0.06(1) pg . These ohservatiors a r e related to the exchange paths and covalency in the compound.

'New insights into an old molecule : interaction energies of theophylline crystal forms.', Crystal growth design., 12 (3). pp. 1395-1401. Further information on publisher's website:http://dx.doi.org/10.1021/cg201499sPublisher's copyright statement:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Crystal growth design, copyright c American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://dx.doi.org/10.1021/cg201499sAdditional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO• the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. The asthma therapeutic theophylline exists in at least three anhydrous polymorphs and a monohydrate. The single-crystal X-ray structure of the high-temperature polymorph form I is presented for the first time and the energetic relationship between forms I and II is investigated using the partial charges and chemical hardness analysis (PACHA) algorithm. It is shown that the interactions in the form I crystal network are stronger, especially the hydrogen bond. The singlecrystal neutron structure of the monohydrate demonstrates static disorder of the water molecule as well as dynamic disorder of the methyl groups. PACHA investigations based on the neutron coordinates reveal that the homomeric interactions in this form are stronger than the interaction of the water with the host molecules. The dehydration of the hydrate should thus leave the theophylline network intact, explaining the isomorphic powder X-ray diffractograms of the monohydrate and its dehydrated form III.

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