Steric self-assembly of laterally confined organic semiconductor molecule analogues.

Self-assembly of planar molecules can be a critical route to control morphology in organic optoelectronic systems. In this study, Monte Carlo simulations were performed with polygonal disc analogues to planar semiconducting molecules under confinement. By examining statistically the molecular density and configurations of such analogues, we have observed that the symmetry of the confining medium can have a greater impact on the final densified particle configurations than the intramolecular interactions.

X-ray cross correlation analysis uncovers hidden local symmetries in disordered matter.

We explore the different local symmetries in colloidal glasses beyond the standard pair correlation analysis. Using our newly developed X-ray cross correlation analysis (XCCA) concept together with brilliant coherent X-ray sources, we have been able to access and classify the otherwise hidden local order within disorder. The emerging local symmetries are coupled to distinct momentum transfer (Q) values, which do not coincide with the maxima of the amorphous structure factor.

Expanding micelle nanolithography to the self-assembly of multicomponent core-shell nanoparticles.

Size, composition, and pattern formation are crucial elements in the fabrication of functional multicomponent nanoparticles (NPs). Self-assembly techniques provide relevant control over NP size distribution (down to a few nanometers in diameter), but more importantly, such techniques are amenable for practical applications since the resulting NPs (and arrays thereof) are programmed in the molecular structure of the precursors. Here, the diblock copolymer micelle nanolithography concept of achieving monodisperse NPs is extended to direct the synthesis of multicomponent core-shell NPs arranged in a triangular lattice.

Long-wavelength elastic interactions in complex crystals.

The long-wavelength (LWL) limit of the elastic interactions in complex non-Bravais lattices is investigated on the basis of microscopic elasticity theory. The conceptual simplicity of our approach enables large-scale simulations in materials with complex crystalline structures. We demonstrate the method by calculating the LWL elastic energy of hcp-based Mg binary alloys for a variety of impurities.

Cluster expansions in multicomponent systems: precise expansions from noisy databases.

We have performed a systematic analysis of the numerical errors contained in the databases used in cluster expansions of multicomponent alloys. Our results underscore the importance of numerical noise in the determination of the effective cluster interactions and in the expansion determination. The relevance of the size of and information contained in the input database is highlighted.

Ordering and magnetism in Fe-Co: dense sequence of ground-state structures.

We discover that Fe-Co alloys develop a series of ordered ground-state structures in addition to the known CsCl-type structure. This new set of structures is found from a combinatorial ground-state search of 1.5 x 10(10) bcc-based structures.