A. Spek | Semantic Scholar

Publications
Influence

Structure validation in chemical crystallography

A. Spek
Chemistry, Materials Science
Acta crystallographica. Section D, Biological…
20 January 2009

This paper reports on the current status of structure validation in chemical crystallography and describes the current state of research in this area.

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Single-crystal structure validation with the program PLATON

A. Spek
Chemistry
1 February 2003

The results of a single-crystal structure determination when in CIF format can now be validated routinely by automatic procedures, and the concepts of validation and the classes of checks carried out by the program PLATON as part of the IUCr checkCIF facility are described.

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Determination of absolute structure using Bayesian statistics on Bijvoet differences

Rob W.W. Hooft, L. Straver, A. Spek
Chemistry
Journal of applied crystallography
16 January 2008

A description is given of a maximum-likelihood approach to absolute structure determinations of biologically active molecules and how this approach can be applied to solve the mystery of why polyene-like structures occur in nature.

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checkCIF validation ALERTS: what they mean and how to respond

A. Spek
Computer Science
Acta crystallographica. Section E…
1 January 2020

This paper provides additional background information on the checkCIF procedure and additional details for a number of ALERTS along with options for how to act on them.

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PLATON SQUEEZE: a tool for the calculation of the disordered solvent contribution to the calculated structure factors.

A. Spek
Chemistry
Acta crystallographica. Section C, Structural…
2015

The SQUEEZE method is documents as an alternative means of addressing the solvent disorder issue and conveniently interfaces with the 2014 version of the least-squares refinement program SHELXL, and many twinned structures containing disordered solvents are now also treatable by SQUEEze.

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Crystal Structure Refinement

Peter Müller, R. Herbst‐Irmer, A. Spek, T. Schneider, M. Sawaya
Chemistry
13 July 2006

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BYPASS: an effective method for the refinement of crystal structures containing disordered solvent regions

P. Sluis, A. Spek
Chemistry
1 March 1990

A method is described for the least-squares refinement of the atomic parameters of the ordered part of a crystal structure in the presence of disordered solvent areas. Potential solvent regions are…

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Using the t‐distribution to improve the absolute structure assignment with likelihood calculations

R. Hooft, L. Straver, A. Spek
Geology
1 August 2010

The previously described method for absolute structure determination [Hooft, Straver & Spek (2008). J. Appl. Cryst. 41, 96–103] assumes a Gaussian error distribution. The method is now extended to…

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Single-crystal structure validation with the program

A. Spek
Chemistry
2003

The results of a single-crystal structure determination when in CIF format can now be validated routinely by automatic procedures. In this way, many errors in published papers can be avoided. The…

STRONG DIMERIZATION OF UREIDOPYRIMIDONES VIA QUADRUPLE HYDROGEN BONDING

F. H. Beijer, R. Sijbesma, H. Kooijman, A. Spek, E. W. Meijer
Chemistry
27 June 1998

6-Methyl-2-butylureidopyrimidone dimerizes via four hydrogen bonds in the solid state as well as in CHCl3 solution via a donor−donor−acceptor−acceptor (DDAA) array of hydrogen bonding sites in the…

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