Experimental and computational growth morphology of two polymorphs of a yellow isoxazolone dye

Contains fulltext : 32488.pdf (publisher's version ) (Closed access

MONTY: Monte Carlo crystal growth on any crystal structure in any crystallographic orientation; Application to fats

Contains fulltext : 60517.pdf (publisher's version ) (Closed access)A versatile crystal-growth simulation program, based on the Monte Carlo algorithm, is introduced. It enables the handling of any crystallographic orientation. The crystal is modeled by a set of molecular interactions, which are obtained from molecular mechanics calculations. The motherphase is parametrized by its bulk thermodynamic properties. As an example, the program was used to simulate the growth of various fat crystals. The results show the importance of the details of the crystal structure, its energetics, and the actual growth conditions upon the crystal morphology. The model intends to fill the gap which exists by the fact that supersaturation, temperature, concentration, and dissolution free energy are not taken into account by the established morphology prediction models

A phase-field/Monte-Carlo model describing organic crystal growth from solution

68.35.Ct Interface structure and roughness, 68.43.Mn Adsorption kinetics, 68.55.Ac Nucleation and growth: microscopic aspects,

A third blind test of crystal structure prediction

Following the interest generated by two previous blind tests of crystal structure prediction (CSP1999 and CSP2001), a third such collaborative project (CSP2004) was hosted by the Cambridge Crystallographic Data Centre. A range of methodologies used in searching for and ranking the likelihood of predicted crystal structures is represented amongst the 18 participating research groups, although most are based on the global minimization of the lattice energy. Initially the participants were given molecular diagrams of three molecules and asked to submit three predictions for the most likely crystal structure of each. Unlike earlier blind tests, no restriction was placed on the possible space group of the target crystal structures. Furthermore, Z' = 2 structures were allowed. Part-way through the test, a partial structure report was discovered for one of the molecules, which could no longer be considered a blind test. Hence, a second molecule from the same category (small, rigid with common atom types) was offered to the participants as a replacement. Success rates within the three submitted predictions were lower than in the previous tests - there was only one successful prediction for any of the three 'blind' molecules. For the 'simplest' rigid molecule, this lack of success is partly due to the observed structure crystallizing with two molecules in the asymmetric unit. As in the 2001 blind test, there was no success in predicting the structure of the flexible molecule. The results highlight the necessity for better energy models, capable of simultaneously describing conformational and packing energies with high accuracy. There is also a need for improvements in search procedures for crystals with more than one independent molecule, as well as for molecules with conformational flexibility. These are necessary requirements for the prediction of possible thermodynamically favoured polymorphs. Which of these are actually realised is also influenced by as yet insufficiently understood processes of nucleation and crystal growth