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Crystal Structure Prediction based on Statistical Potentials (1998)

Hofmann, Detlef W. M. ; Lengauer, Thomas

Springer

Journal of molecular modeling 4 (1998), S. 132-144

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ISSN: 0948-5023

Keywords: Keywords Crystal structure prediction ; Statistical potentials ; Similarity of crystals ; Discrete molecular modeling

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract Organic molecule crystals are becoming more and more important in applications like piezoelectricity, ferroelectricity and pigments. These properties depend on the molecule and on the crystal structure. For this reason much effort is being made to predict the crystal structure of organic molecules. We have developed a new algorithm differing mainly in three features from other approaches (simulated annealing, Monte Carlo etc.). First, we analyze just one molecule for proper symmetry operations building up the crystal; second, the program works in a discrete space; and finally the scoring function (energy function) is derived statistically from known crystal structures and tabulated. Our program computes a list of crystal structures weighted according to our scoring function. The new algorithm FlexCryst is currently implemented for the four space groups P1, Pbar1, P21, and P212121. The three latter space groups are widespread in nature. The algorithm computes structural models of acceptable quality and shows excellent time performance. During our validation we found the experimental structure among the structures proposed by the algorithm in 123 of 129 cases for P1, in 66 of 95 cases for Pbar1, in 73 of 100 cases for P21, and in 94 of 98 cases for P212121. The performance depends on the space group. In the case of P1 the run time per molecule is about two minutes and increases up to roughly one hour for the space group P21.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s008940050130

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A test of crystal structure prediction of small organic molecules (2000)

Lommerse, Jos P. M. ; Motherwell, W. D. Sam ; Ammon, Herman L. ; [et al.]

Copenhagen : International Union of Crystallography (IUCr)

Acta crystallographica 56 (2000), S. 697-714

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ISSN: 1600-5740

Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001

Topics: Chemistry and Pharmacology , Geosciences , Physics

Notes: A collaborative workshop was held in May 1999 at the Cambridge Crystallographic Data Centre to test how well currently available methods of crystal structure prediction perform when given only the atomic connectivity for an organic compound. A blind test was conducted on a selection of four compounds and a wide range of methodologies representing the principal computer programs currently available were used. There were 11 participants who were allowed to propose at most three structures for each compound. No program gave consistently reliable results. However, seven proposed structures were close to an experimental one and were classified as `correct'. One compound occurred in two polymorphs, but only one form was predicted correctly among the calculated structures. The basic problem with lattice energy based methods of crystal structure prediction is that many structures are found within a few kJ mol−1 of the global minimum. The fine detail of the force-field methodology and parametrization influences the energy ranking within each method. Nevertheless, present methods may be useful in providing a set of structures as possible polymorphs for a given molecular structure.