DASH Software

Structure Solution from Powder Diffraction Data

DASH is a versatile and interactive package for solving crystal structures from powder diffraction data. DASH solves structures by simulated annealing of structural models to indexed diffraction data and features a helpful wizard to guide you through the entire structure solution process.

 


 

Subscribers to the Cambridge Structural Database System (CSDS) benefit from direct links with Mogul for the automatic assessment and use of torsional restraints during structure solution. Biasing conformational searching towards torsion angle ranges commonly observed in crystal structures has been shown to give, on average, a 40% reduction in the number of moves required to solve the structure compared to unconstrained runs. This not only speeds up structure solution but can also make challenging problems tractable.

A molecular structure created from a powder pattern with DASH software

Verapamil hydrochloride, a salt complex with 13 torsional degrees of freedom, is an example of a particularly challenging structure that was solved using DASH

 

CSD REFCODE: CURHOM

DASH accepts both synchrotron and monochromatic laboratory X-ray powder diffraction data in a wide variety of common file formats. The program has been successful in solving the structures of many systems of both academic and industrial interest. At the upper level of complexity, DASH has solved structures for molecules comprising up to 16 flexible torsion angles, more than 72 non-hydrogen atoms, and up to six molecules in the asymmetric unit.

 

DASH has been successfully used to solve a diverse array of structure types including pharmaceutical compounds (e.g. naltrexone hydrochloride), salts (e.g. amodiaquinium dichloride dehydrate), solvates (e.g. chlorothiazide N,N-dimethylformamide solvate), semiconductors (e.g. lithium 1,8,15,22-tetraphenoxyphthalocyanine) and explosives (e.g. silver azide). DASH is also routinely applied to the solution of organometallic crystal structures and has been used to solve inorganic crystal structures.


FAQs

The program DASH1, which has been distributed by the CCDC since the public release of version 1.0 in April 2001, is one of the most well-known and successful packages for crystal structure solution from powder diffraction data. The concepts behind DASH, as well as the initial software package, were first developed and published by Bill David, Kenneth Shankland, and Norman Shankland in 19982.

The software was then taken on by the CCDC to support, maintain and distribute, and DASH has also been the subject of a long-term, successful collaboration with the originators including many software and scientific improvements made over the years both by the CCDC and by the research groups of Bill David, Kenneth Shankland, and Norman Shankland. Recent research and improvements include the work done by Kabova, Shankland, and co-workers to illustrate the benefits of using conformational information (Mogul) to help solve structures3 and to fine-tune the parameters of the simulated annealing algorithm at the heart of DASH4.

The functionality of DASH is now at the periphery of the CSD software portfolio, and as such we have not been able to spend much time developing its functionality in recent years. To make sure DASH continues to be available to use, and has the chance to grow and change, we have made it available as open source on GitHub. This allows anybody to download and use DASH, and also contribute to developing it further.

This change gives our team more time to focus on other developments within the CSD-Materials suite.

Since December 2021, DASH is no longer installed as part of the CSD installation.

In March 2022, older versions of DASH stopped working.

You now need to download DASH from the CCDC Open Source GitHub project in the DASH repository here.

You do not need a CSD licence to access or use DASH, but the effectiveness of structure solution in DASH is still enhanced by CSD data (as shown by Kabova and co-workers4) if you do have an active CSD licence via the link to Mogul conformational data. The CCDC will continue to test and maintain the interface mechanism to Mogul data going forward to ensure this remains functional. You can also still visualise solved structures in Mercury using either the free version of Mercury or the CSD licensed version.

If you want to make changes or develop DASH functionality, you can contribute through GitHub.

DASH is now available for free, for anyone to use and adapt under the MIT licence.

This means the code is openly accessible on GitHub where anyone can work on improving or extending the code. You can also report concerns or improvement ideas to the community within GitHub.

Learn more about this licence on the Open Source Initiative website here.

DASH became available in the CCDC Open Source GitHub project in November 2021.

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Questions? Try our FAQs or contact the CCDC team.

  1. DASH: a program for Crystal Structure Determination from Powder Diffraction Data. W. I. F. David, K Shankland, J. van de Streek, E. Pidcock, W. D. S. Motherwell, J. C. Cole. J. Appl. Cryst., 39, 910-915, 2006. DOI: 10.1107/S0021889806042117
  2. Routine Determination of Molecular Crystal Structures from Powder Diffraction Data. W. I. F. David, K. Shankland, N. Shankland, Chem. Commun., 931-932, 1998. DOI: 10.1039/a800855h
  3. Improved crystal structure solution from powder diffraction data by the use of conformational information. E. A. Kabova, J. C. Cole, O. Korb, A. C. Williams, K. Shankland, J. Appl. Crystallogr., 2017, 50 1421-1427. DOI: 10.1107/S1600576717012596
  4. Improved performance of crystal structure solution from powder diffraction data through parameter tuning of a simulated annealing algorithm. E. A. Kabova, J. C. Cole, O. Korb, M. Lopez-Ibanez, A. C. Williams, K. Shankland, J. Appl. Crystallogr., 2017, 50 1411-1420. DOI: 10.1107/S1600576717012602