University of Arkansas

About: University of Arkansas is a education organization based out in Fayetteville, Arkansas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 17225 authors who have published 33329 publications receiving 941102 citations. The organization is also known as: Arkansas & UA.

Electronic and optical properties of strained graphene and other strained 2D materials: a review

Abstract: This review presents the state of the art in strain and ripple-induced effects on the electronic and optical properties of graphene. It starts by providing the crystallographic description of mechanical deformations, as well as the diffraction pattern for different kinds of representative deformation fields. Then, the focus turns to the unique elastic properties of graphene, and to how strain is produced. Thereafter, various theoretical approaches used to study the electronic properties of strained graphene are examined, discussing the advantages of each. These approaches provide a platform to describe exotic properties, such as a fractal spectrum related with quasicrystals, a mixed Dirac-Schrodinger behavior, emergent gravity, topological insulator states, in molecular graphene and other 2D discrete lattices. The physical consequences of strain on the optical properties are reviewed next, with a focus on the Raman spectrum. At the same time, recent advances to tune the optical conductivity of graphene by strain engineering are given, which open new paths in device applications. Finally, a brief review of strain effects in multilayered graphene and other promising 2D materials like silicene and materials based on other group-IV elements, phosphorene, dichalcogenide- and monochalcogenide-monolayers is presented, with a brief discussion of interplays among strain, thermal effects, and illumination in the latter material family.

Comparison of the boys and Pipek-Mezey localizations in the local correlation approach and automatic virtual basis selection

Abstract: Our implementation of Pipek-Mezey population localization is described. It is compared with other localization schemes and its use in the framework of the local correlation method is discussed. For such use, this localization is shown to be clearly superior to Boys in the case of physically well-localized systems. Our current algorithm for selection of local virtual spaces is also described

A Network Analysis of Global Banking: 1978-2010

Abstract: We analyze the global banking network using data on cross-border banking flows for 184 countries during 1978–2010. We find that the density of the global banking network defined by these flows is procyclical, expanding and contracting with the global cycle of capital flows. We also find that country connectedness in the network tends to rise before banking and debt crises and to fall in their aftermath. Despite a historically unique build-up in aggregate flows prior to the global financial crisis, network density in 2007 was comparable to earlier peaks. This suggests that factors other than connectedness, such as the location of the initial shock to the core of the network, have contributed to the severity of the crisis. The global financial crisis stands out as an unusually large perturbation to the global banking network, with indicators of network density in 2008 reaching all-time lows.

Molecular Dynamics Modeling of Clay Minerals. 1. Gibbsite, Kaolinite, Pyrophyllite, and Beidellite

Abstract: A molecular dynamics model for clays and the oxide minerals is desirable for studying the kinetics and thermodynamics of adsorption processes. To this end, a valence force field for aluminous, dioctahedral clay minerals was developed. Novel aspects of this development include the bending potential for octahedral O−Al−O angles, which uses a quartic polynomial to create a double-well potential with minima at both 90° and 180°. Also, atomic point charges were derived from comparisons of ab initio molecular electrostatic potentials with X-ray diffraction-based deformation electron densities. Isothermal−isobaric molecular dynamics simulations of quartz, gibbsite, kaolinite, and pyrophyllite were used to refine the potential energy parameters. The resultant force field reproduced all the major structural parameters of these minerals to within 1% of their experimentally determined values. Transferability of the force field to simulations of adsorption onto clay mineral surfaces was tested through simulations of ...