Localized defect regions within two-dimensional photonic crystal slab waveguides are an attractive method of forming high-quality factor optical resonators with wavelength-scale modal volumes. Using simple symmetry bases, and the tools of group theory, we develop an approximate description of the resonant modes of different photonic crystal defect cavities. Comparison to numerical simulations a...

has been investigated. The crystal structure of strontium niobate depends on the Sr content of the A site, with cubic symmetry for Sr ≤ 0.92 and orthorhombic symmetric for 0.92 ˂ Sr ≤ 0.97. The change of crystal structure from cubic to orthorhombic symmetry seems to have a negative effect on the photocatalytic activity, as the NbO6 octahedra become distorted and unfavourable for d-orbital overl...

In the crystal structure of the title salt, (C(7)H(7)N(2)S)(2)[Mn(C(8)H(8)O(5))(2)]·6H(2)O, the heterocyclic N atom of the 2-amino-benzothia-zole mol-ecule is protonated. The Mn(II) atom (site symmetry ) has a slightly distorted octa-hedral MnO(6) coordination defined by the bridging O atoms of the bicyclo-heptane unit and four carboxyl-ate O atoms of two symmetry-related and fully deprotonated...

A second polymorph of the title compound, C21H16N4, is reported. The original polymorph was solved by our group [Matsumoto et al. (2003 ▶). Tetra-hedron Lett. 44, 2861-2864] in the monoclinic space group C2/c and refined to R = 0.050. Now the crystal structure of a tetra-gonal polymorph (space group P-421 c) has been solved and refined to R = 0.036. In the crystal, there are no strong inter-mol...

The asymmetric unit of the title compound, C10H8N2S2, is composed of two independent half-mol-ecules, each residing on a center of symmetry. In the crystal, weak C-H⋯π inter-actions join the two symmetry-independent molecules together into interlinked chains parallel to [011]. The crystal structure was refined as a two-component pseudo-merohedral twin using the twin law 001 0-10 100. The refine...

This perspective article elucidates both the importance and implications of relativistic spacetime crystals as well renormalized blended coordinates transformation. It alludes to possible applications in materials science, condensed matter physics quantum gravity.

Despite the development of crystal engineering, it remains a great challenge to predict the crystal structure even for the simplest molecules, and a clear link between molecular and crystal symmetry is missing in general. Here we demonstrate that the two-dimensional (2D) crystallization of heterocirculenes on a Au(111) surface is greatly affected by the molecular symmetry. By means of ultrahigh...

A quantisation of chiral symmetry within the Skyrme crystal is carried out. The definition of global isospin in the crystal is explored, and found to be ambiguous. However, the state corresponding to a neutron crystal is identified, and the leading quantum correction to the classical mass is computed. The results are compared to those of Klebanov for a crystal of whole skyrmions.

A method to predict crystal structures of crystaline drugs by systematic searching for minimum-energy packings is outlined. It bases on the use of the observed space-group occurrence factors to postulate crystal symmetry. The search region is chosen within the fundamental unit of multi-dimensional crystal-structure parameter space, including the cell parameters and rigidbody mlecular parameters...