ИСТИНА

The ATSAS software package (Manalastas-Cantos et al., 2021) provides a number of widely used applications for data analysis and modelling in the field of biological small angle scattering of biological macromolecules. During the two years since its previous major release, significant efforts were made to improve not only the accuracy and performance of these applications, but also their usability and accountability. In particular, the application to calculate scattering patterns from atomic coordinates, CRYSOL (Svergun et al., 1995) was re-implemented with modern software design principles. In addition to all its previous functionality, CRYSOL now includes an alternative water-shell implementation and individual form factors for dummy residues. CRYSOL can be used directly on dummy atom models, handle both PDB and mmCIF formatted files, and has been seamlessly integrated into various other applications. All data sources used by CRYSOL, e.g. Cromer-Mann form-factor coefficients, dummy residue form-factors or anomalous SAXS energy correction terms, are available as open mmCIF data and are user-verifiable, configurable and extensible. As Python became a popular platform for scientific application development, native Python bindings for CRYSOL are provided as a proof-of-principle and test for the community. The ab initio modelling post-processing suite DAMAVER (Volkov & Svergun, 2003) was consolidated into a single program, that also allows to utilize multiple similarity measures. Further, DAMAVER, as well as most other analysis and modelling applications of the ATSAS package, received performance improvements. The speed up factors range from small, but noticeable gains for some applications to orders of magnitude for others. This was achieved by replacing key algorithms in addition to careful application of CPU-based multithreading via OpenMP (www.openmp.org). Additional gain was provided by platform specific performance libraries for common linear algebra operations (LAPACK). The graphical user interface PRIMUS was modernized and extended. A ribbon-style toolbar was implemented with a new icon theme that supports light and dark modes to provide convenient access. The data comparison now provides alternative views of expected and observed distributions of residuals or chi-square values to aid the assessment of the accuracy of error estimates. Additional wizards, e.g. for hybrid modelling applications (predict and fit modes) have been included. The ATSAS-3.1 installer package is available for download on all major software platforms (Linux, MacOS and Windows) and is free of charge for academic users (https://www.embl-hamburg.de/biosaxs/software.html). References Manalastas-Cantos, K., Konarev, P.V., Hajizadeh, N.R., Kikhney, A.G., Petoukhov, M.V., Molodenskiy, D.S., Panjkovich, A., Mertens, H.D.T., Gruzinov, A., Borges, C., Jeffries, C.M., Svergun, D.I., Franke, D. ATSAS 3.0: expanded functionality and new tools for small-angle scattering data analysis J. Appl. Cryst. 54, 343–355 (2021) https://doi.org/10.1107/S1600576720013412 Svergun D.I., Barberato C. and Koch M.H.J. CRYSOL - a Program to Evaluate X-ray Solution Scattering of Biological Macromolecules from Atomic Coordinates. J. Appl. Cryst. 28, 768-773 (1995)http://doi.org/10.1107/S0021889895007047 Volkov V.V. and Svergun D.I. Uniqueness of ab initio shape determination in small-angle scattering. J. Appl. Cryst. 36, 860-864 (2003) https://doi.org/10.1107/S0021889803000268