scholarly journals Towards ab initio screening of co-crystal formation through lattice energy calculations and crystal structure prediction of nicotinamide, isonicotinamide, picolinamide and paracetamol multi-component crystals

CrystEngComm ◽  
2013 ◽  
Vol 15 (19) ◽  
pp. 3799 ◽  
Author(s):  
H. C. Stephen Chan ◽  
John Kendrick ◽  
Marcus A. Neumann ◽  
Frank J. J. Leusen
Keyword(s):  
Crystal Structure ◽  
Ab Initio ◽  
Structure Prediction ◽  
Lattice Energy ◽  
Crystal Formation ◽  
Crystal Structure Prediction ◽  
Energy Calculations

Crystal structure prediction of LiBeH3 using ab initio total-energy calculations and evolutionary simulations

2008 ◽  
Vol 129 (23) ◽  
pp. 234105 ◽  
Author(s):  
Chao-Hao Hu ◽  
A. R. Oganov ◽  
Y. M. Wang ◽  
H. Y. Zhou ◽  
A. Lyakhov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Total Energy ◽  
Ab Initio ◽  
Structure Prediction ◽  
Crystal Structure Prediction ◽  
Energy Calculations ◽  
Evolutionary Simulations

scholarly journals New high-pressure phases of Fe7N3 and Fe7C3 stable at Earth's core conditions: evidences for carbon–nitrogen isomorphism in Fe-compounds

RSC Advances ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 3577-3581 ◽  
Author(s):  
Nursultan Sagatov ◽  
Pavel N. Gavryushkin ◽  
Talgat M. Inerbaev ◽  
Konstantin D. Litasov
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Ab Initio ◽  
Structure Prediction ◽  
Harmonic Approximation ◽  
Crystal Structure Prediction ◽  
Earth’S Core ◽  
Earth's Core ◽  
Core Conditions

We carried out ab initio calculations on the crystal structure prediction and determination of P–T diagrams within the quasi-harmonic approximation for Fe7N3 and Fe7C3.

scholarly journals Blind crystal structure prediction of a novel second polymorph of 1-hydroxy-7-azabenzotriazole

2006 ◽  
Vol 62 (4) ◽  
pp. 642-650 ◽  
Author(s):  
Harriott Nowell ◽  
Christopher S. Frampton ◽  
Julie Waite ◽  
Sarah L. Price
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Structure Refinement ◽  
Lattice Energy ◽  
Polymorphic Form ◽  
Crystal Structure Prediction ◽  
Blind Test ◽  
Coupling Reagent ◽  
Energy Penalty ◽  
Alcohol Solvents

The commercially available peptide coupling reagent 1-hydroxy-7-azabenzotriazole has been shown to crystallize in two polymorphic forms. The two polymorphs differ in their hydrogen-bonding motif, with form I having an R_2^2(10) dimer motif and form II having a C(5) chain motif. The previously unreported form II was used as an informal blind test of computational crystal structure prediction for flexible molecules. The crystal structure of form II has been successfully predicted blind from lattice-energy minimization calculations following a series of searches using a large number of rigid conformers. The structure for form II was the third lowest in energy with form I found as the global minimum, with the energy calculated as the sum of the ab initio intramolecular energy penalty for conformational distortion and the intermolecular lattice energy which is calculated from a distributed multipole representation of the charge density. The predicted structure was sufficiently close to the experimental structure that it could be used as a starting model for crystal structure refinement. A subsequent limited polymorph screen failed to yield a third polymorphic form, but demonstrated that alcohol solvents are implicated in the formation of the form I dimer structure.

scholarly journals Insight from energy surfaces: structure prediction by lattice energy exploration

2014 ◽  
Vol 70 (a1) ◽  
pp. C28-C28
Author(s):  
Graeme Day
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Crystal Packing ◽  
Lattice Energy ◽  
Organic Crystals ◽  
Crystal Structure Prediction ◽  
Stability Order ◽  
The Stability ◽  
Solid Form ◽  
Energy Surfaces

A long-standing challenge for the application of computational chemistry in the field of crystallography is the prediction of crystal packing, given no more than the chemical bonding of the molecules being crystallised. Recent years have seen significant progress towards reliable crystal structure prediction methods, even for traditionally challenging systems involving flexible molecules and multi-component solids [1]. These methods are based on global searches of the lattice energy surface: a search is performed to locate all possible packing arrangements, and these structures are ranked by their calculated energy [2]. One aim of this lecture is to provide an overview of advances in methods for crystal structure prediction, focussing on molecular organic crystals, and highlighting strategies that are being explored to extend the reach of these methods to more complex systems. A second aim is to discuss the range applications of crystal structure prediction calculations, which have traditionally included solid form screening, particularly of pharmaceutically active molecules, and structure determination. As energy models become more reliable at correctly ranking the stability order of putative structures, and the timescale required for structure searching decreases, crystal structure prediction has the potential for the discovery of novel molecular materials with targeted properties. Prospects for computer-guided discovery of materials will be discussed.

Molecular packing groups and ab initio crystal-structure prediction

1999 ◽  
Vol 55 (4) ◽  
pp. 621-627 ◽  
Author(s):  
Daquan Gao ◽  
Donald E. Williams
Keyword(s):  
Crystal Structure ◽  
Ab Initio ◽  
Energy Minimization ◽  
Structure Prediction ◽  
Group Symmetry ◽  
Crystal Structure Prediction ◽  
Asymmetric Unit ◽  
Efficient Procedure ◽  
Space Groups ◽  
Independent Molecules

Ab initio crystal structure prediction can proceed by minimization of the packing energy of Z independent molecules per cell, or alternatively by energy minimization taking one molecule as independent and Z-1 molecules as related by assumed space-group symmetry. In the former method, a large number of positional variables must be considered. In the latter method, a large number of space groups must be considered. An alternative, more efficient, procedure is proposed, where it is recognized that values of Z and the number of molecules in the asymmetric unit, Z′, impose restrictions on possible space groups. Examples of application of this method to crystal structure prediction are given.

The polymorphs of ROY: application of a systematic crystal structure prediction technique

2012 ◽  
Vol 68 (6) ◽  
pp. 677-685 ◽  
Author(s):  
Manolis Vasileiadis ◽  
Andrei V. Kazantsev ◽  
Panagiotis G. Karamertzanis ◽  
Claire S. Adjiman ◽  
Constantinos C. Pantelides
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Search Algorithm ◽  
Lattice Energy ◽  
Relative Energy ◽  
Quantum Mechanical ◽  
Crystal Structure Prediction ◽  
Worst Case ◽  
Prediction Technique ◽  
Prediction Techniques

We investigate the ability of current ab initio crystal structure prediction techniques to identify the polymorphs of 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile, also known as ROY because of the red, orange and yellow colours of its polymorphs. We use a methodology combining the generation of a large number of structures based on a computationally inexpensive model using the CrystalPredictor global search algorithm, and the further minimization of the most promising of these structures using the CrystalOptimizer local minimization algorithm which employs an accurate, yet efficiently constructed, model based on isolated-molecule quantum-mechanical calculations. We demonstrate that this approach successfully predicts the seven experimentally resolved structures of ROY as lattice-energy minima, with five of these structures being within the 12 lowest energy structures predicted. Some of the other low-energy structures identified are likely candidates for the still unresolved polymorphs of this molecule. The relative stability of the predicted structures only partially matches that of the experimentally resolved polymorphs. The worst case is that of polymorph ON, whose relative energy with respect to Y is overestimated by 6.65 kJ mol−1. This highlights the need for further developments in the accuracy of the energy calculations.

Structural investigation ofN,N′-methylenebisacrylamideviaX-ray diffraction assisted by crystal structure prediction

2015 ◽  
Vol 48 (2) ◽  
pp. 550-557 ◽  
Author(s):  
Claudia Graiff ◽  
Daniele Pontiroli ◽  
Laura Bergamonti ◽  
Chiara Cavallari ◽  
Pier Paolo Lottici ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Structure Prediction ◽  
Density Functional ◽  
Geometry Optimization ◽  
Lattice Energy ◽  
Strong Interactions ◽  
Crystal Structure Prediction ◽  
X Ray Diffraction ◽  
X Ray

The crystal structure ofN,N′-methylenebisacrylamide was determined through the geometry optimization of the molecular unit with density functional theory and conformational analysis, and then through the calculation of the packingviaa crystal structure prediction protocol, based on lattice energy minimization. All the calculated structures were ranked, comparing their powder pattern with the laboratory low-quality X-ray diffraction data. Rietveld refinement of the best three proposed structures allowed the most probable crystal arrangement of the molecules to be obtained. This approach was essential for disentangling the twinning problems affecting the single-crystal X-ray diffraction data, collected on samples obtainedviarecrystallization of powder, which definitely confirmed the predicted model. It was found thatN,N′-methylenebisacrylamide shows a monoclinic structure in the space groupC2/c, with lattice parametersa= 17.822 (12),b= 4.850 (3),c= 19.783 (14) Å, β = 102.370 (9)°,V= 1670 (2) Å3. Two strong interactions between the amide protons and the carbonyl groups of neighbouring molecules were found along thebaxis, determining the crystal growth in the form of wires in this direction. This work provides a further example of how computational methods may help to investigate low-quality molecular crystals with standard diffraction techniques.

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