Systematic prediction of crystal structures

Winkler, Björn; Pickard, Chris J.; Milman, Victor; Thimm, Georg

doi:10.1016/s0009-2614(01)00126-9

Cited by 56 publications

(33 citation statements)

References 27 publications

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“…The scope of these methods has improved in recent years, providing the ability to predict possible stable phases of a wide range of materials. For example, these methods have been used for the successful prediction of single [18][19][20][21][22] and multicomponent 19,[23][24][25][26] organic molecular crystals [27][28][29][30] , high-pressure phases of materials [31][32][33] , and other crystalline network structures such as zeolites or carbon polymorphs [34][35][36] . Progress in this field for organic molecular crystals is regularly assessed in a series of blind tests of structure prediction 37 .…”

Section: Introductionmentioning

confidence: 99%

Powder crystallography of pharmaceutical materials by combined crystal structure prediction and solid-state 1H NMR spectroscopy

Baias

Widdifield

Dumez

et al. 2013

Phys. Chem. Chem. Phys.

162

251

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A protocol for the ab initio crystal structure determination of powdered solids at natural isotopic abundance by combining solid-state NMR spectroscopy, crystal structure prediction, and DFT chemical shift calculations was evaluated to determine the crystal structures of four small drug molecules: cocaine, flutamide, flufenamic acid, and theophylline. For cocaine, flutamide and flufenamic acid, we find that the assigned 1 H isotropic chemical shifts provide sufficient discrimination to determine the correct structures from a set of predicted structures using the root-mean-square deviation (rmsd) between experimentally determined and calculated chemical shifts. In most cases unassigned shifts could not be used to determine the structures. This method requires no prior knowledge of the crystal structure, and was used to determine the correct crystal structure to within an atomic rmsd of less than 0.12 Å with respect to the known reference structure. For theophylline, the NMR spectra are too simple to allow for unambiguous structure selection.

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Section: Introductionmentioning

confidence: 99%

Powder crystallography of pharmaceutical materials by combined crystal structure prediction and solid-state 1H NMR spectroscopy

Baias

Widdifield

Dumez

et al. 2013

Phys. Chem. Chem. Phys.

162

251

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“…We investigated all possible networks (13) with up to six vertices in the unit cell, as obtained from an exhaustive search originally applied to carbon polymorphs [25]. We also considered a layered structure based upon the topology of graphite (Fig.…”

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confidence: 99%

“…The structure numbering corresponds to the order of appearance in table 1 of Ref. 25. We rejected the structure T12, corresponding to the 6(3)5-09 net in Ref.…”

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confidence: 99%

Hidden polymorphs drive vitrification in B2O3

Ferlat

Seitsonen²,

Lazzeri³

et al. 2012

Nature Mater

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Understanding the conditions which favor crystallisation or vitrification of liquids has been a long-standing scientific problem [1][2][3]. Another connected, and not yet well understood question is the relationship between the glassy and the various possible crystalline forms a system may adopt [4,5]. In this context, B2O3 is a puzzling case of study since i) it is one of the best glass-forming systems despite an apparent lack of lowpressure polymorphism ii) it vitrifies in a glassy form abnormally different from the only known crystalline phase at ambient pressure [6] iii) it never crystallises from the melt unless pressure is applied, an intriguing behaviour known as the crystallisation anomaly [7][8][9]. Here, by means of ab-initio calculations, we discover the existence of novel B2O3 crystalline polymorphs with structural properties similar to the glass and formation energies comparable to the known ambient crystal. The resulting configurational degeneracy drives the system vitrification at ambient pressure. The degeneracy is lifted under pressure, unveiling the origin of the crystallisation anomaly. This work reconciles the behaviour of B2O3 with that from other glassy systems and reaffirms the role played by polymorphism in a system's ability to vitrify [10,11]. Some of the predicted crystals are cage-like materials entirely made of three-fold rings, opening new perspectives for the synthesis of boron-based nanoporous materials. PACS numbers:Polymorphism, the possibility for a substance to form several distinct crystalline phases of identical composition, is observed for a wide range of materials. This phenomenon has tremendous importance not only per se for understanding the crystallisation process but also because of practical implications such as the design and control of new materials with specific properties [12], a major issue for the pharmaceutical industry [13]. Indeed, the ability of molecular units to pack in various ways generates crystal phases which generally differ in their physical properties and cohesive energies. Another important implication of polymorphism is related to the glassy state: as pointed out earlier [10,11], glass formation is often prevalent for those materials which are found in a variety of crystalline forms. An obvious example is silica (SiO 2 ), the archetypal glass-former, which at low pressure is found as quartz, cristobalite, keatite, tridymite, coesite and moganite [14]. The existence of these many polytypes illustrate that the structural units, here the SiO 4 tetrahedra, can occur in several conformations with little difference in strain energy, allowing for the possibility of metastable states [14]. The ease of glass formation is usually understood as the result of the system frustration associated to the presence of many minima of comparable energy in the crystal energy landscape (CEL). In the context of organic chemistry, it has also been observed that systems with many almost equi-energetic structures containing a common interchangeable motif, correlate with a t...

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“…To date, thirteen such sp 2 phases (Table 1) have been studied in detail [27][28][29][30][31][32][33][34][35][36][37][38][39]. In the present study, diamond like phases were constructed based on the following four 3D graphites: K 4 (Fig.…”

Section: Methodical Partmentioning

confidence: 99%

Diamond-like phases obtained from nanotubes and three-dimensional graphites

Belenkov

Greshnyakov

2015

Phys. Solid State

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The results of ab initio calculations of the structure and properties of thirteen carbon diamond like phases with atoms located in equivalent crystallographic sites have been presented. The calculations have been performed by the B3LYP GGA method. Nine of the studied phases have been obtained by linking or combining nanotubes, the other four phases have been formed from three dimensional graphites. Two new spiral phases SA3 and SA4 whose precursors are 3D graphites have been studied for the first time. For all phases, structural characteristics, sublimation energies, electron densities of states, and bulk moduli have been determined. The X ray powder diffraction patterns required for identifying new diamond like phases in synthesized carbon materials have also been calculated.

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Systematic prediction of crystal structures

Cited by 56 publications

References 27 publications

Powder crystallography of pharmaceutical materials by combined crystal structure prediction and solid-state 1H NMR spectroscopy

Powder crystallography of pharmaceutical materials by combined crystal structure prediction and solid-state 1H NMR spectroscopy

Hidden polymorphs drive vitrification in B2O3

Diamond-like phases obtained from nanotubes and three-dimensional graphites

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