Optical and electronic functionality arising from controlled defect formation in nanoscale complex oxide lateral epitaxy.

Epitaxial crystallization of complex oxides provides the means to create materials with precisely selected composition, strain, and orientation, thereby controlling their functionalities. Extending this control to nanoscale three-dimensional geometries can be accomplished via a three-dimensional analog of oxide solid-phase epitaxy, lateral epitaxial crystallization. The orientation of crystals within laterally crystallized SrTiO systematically changes from the orientation of the SrTiO substrate.

Development and Implementation of Atomically Anisotropic First-Principles Force Fields: A Benzene Case Study.

π-interactions are an important motif in chemical and biochemical systems. However, due to their anisotropic electron densities and complex balance of intermolecular interactions, aromatic molecules represent an ongoing challenge for accurate and transferable force field development. Historically, force fields for aromatics have not exhibited good accuracy with respect to bulk properties or have only been used to study gas-phase dimers.

Phase Selection and Structure of Low-Defect-Density γ-AlO Created by Epitaxial Crystallization of Amorphous AlO.

A multistep phase sequence following the crystallization of amorphous AlO via solid-phase epitaxy (SPE) points to methods to create low-defect-density thin films of the metastable cubic γ-AlO polymorph. An amorphous AlO thin film on a (0001) α-AlO sapphire substrate initially transforms upon heating to form epitaxial γ-AlO, followed by a transformation to monoclinic θ-AlO, and eventually to α-AlO. Epitaxial γ-AlO layers with low mosaic widths in X-ray rocking curves can be formed via SPE by crystallizing the γ-AlO phase from amorphous AlO and avoiding the microstructural inhomogeneity arising from the spatially inhomogeneous transformation to θ-AlO.

Evidence of an unusual N-H···N hydrogen bond in proteins.

Many residues within proteins adopt conformations that appear to be stabilized by interactions between an amide N-H and the amide N of the previous residue. To explore whether these interactions constitute hydrogen bonds, we characterized the IR stretching frequencies of deuterated variants of proline and the corresponding carbamate, as well as the four proline residues of an Src homology 3 domain protein. The CδD2 stretching frequencies are shifted to lower energies due to hyperconjugation with Ni electron density, and engaging this density via protonation or the formation of the Ni+1-H···Ni interaction ablates this hyperconjugation and thus induces an otherwise difficult to explain blue shift in the C-D absorptions.