Search results for "kiteet"
showing 3 items of 33 documents
Topological polarization, dual invariants, and surface flat band in crystalline insulators
2020
We describe a three-dimensional crystalline topological insulator (TI) phase of matter that exhibits spontaneous polarization. This polarization results from the presence of (approximately) flat bands on the surface of such TIs. These flat bands are a consequence of the bulk-boundary correspondence of polarized topological media, and contrary to related nodal line semimetal phases also containing surface flat bands, they span the entire surface Brillouin zone. We also present an example Hamiltonian exhibiting a Lifshitz transition from the nodal line phase to the TI phase with polarization. Utilizing elasticity tetrads, we show a complete classification of 3D crystalline TI phases and invar…
Role of Weak Hydrogen Bonds and Halogen Bonds in 5-Halo-1,3-dimethyluracils and Their Cocrystals : A Combined Experimental and Computational Study
2016
Seven single crystals containing either N,N-dimethyluracil (DMHU) or one of its 5-halogenated derivatives (DMXU; X = F, Cl, Br, I) were prepared using N,N-dimethylformamide as the crystallization solvent. Single crystal X-ray diffraction and quantum chemical calculations carried out at the spin component scaled local MP2 level of theory were then used to study the intramolecular halogen and nonconventional hydrogen bonds present in the structures. The results were compared to and contrasted with the previously reported data for uracil and its halogenated derivatives. In particular, the intermolecular interactions in DMIU were compared to the halogen and hydrogen bonds in 5-iodouracil that, …
Acoustic wave tunneling across a vacuum gap between two piezoelectric crystals with arbitrary symmetry and orientation
2022
It is not widely appreciated that an acoustic wave can “jump” or “tunnel” across a vacuum gap between two piezoelectric solids, nor has the general case been formulated or studied in detail. Here, we remedy that situation, by presenting a general formalism and approach to study such an acoustic tunneling effect between two arbitrarily oriented anisotropic piezoelectric semi-infinite crystals. The approach allows one to solve for the reflection and transmission coefficients of all the partial-wave modes, and is amenable to practical numerical or even analytical implementation, as we demonstrate by a few chosen examples. The formalism can be used in the future for quantitative studies of the …