Simulating the nanomechanical response of cyclooctatetraene molecules on a graphene device

We investigate the atomic and electronic structures of cyclooctatetraene (COT) molecules on graphene and analyze their dependence on external gate voltage using first-principles calculations. The external gate voltage is simulated by adding or removing electrons using density functional theory (DFT) calculations. This allows us to investigate how changes in carrier density modify the molecular shape, orientation, adsorption site, diffusion barrier, and diffusion path. For increased hole doping COT molecules gradually change their shape to a more flattened conformation and the distance between the molecules and graphene increases while the diffusion barrier drastically decreases. For increased electron doping an abrupt transition to a planar conformation at a carrier density of -8$\times$10$^{13}$ e/cm$^2$ is observed. These calculations imply that the shape and mobility of adsorbed COT molecules can be controlled by externally gating graphene devices

On the analysis of nucleon-nucleon scattering experiments

A method of perturbation calculation, especially adapted to nucleon-nucleon scattering problems, is described. Any contribution to the energy of the system which is relatively small where the nuclear potential is large may be treated as the perturbation. Two principal examples are discussed. (1) Energy as the perturbation: An expansion of the phase shifts in powers of the energy is written down which extends earlier results of Schwinger, Blatt, and Jackson. (2) The Coulomb field as the perturbation in the proton-proton problem: Expansions are given which relate the nuclear phase shifts in a combined nuclear and Coulomb field to the corresponding phase shifts for a purely nuclear problem. Attention is confined to central forces throughout

Oat Yields Depend on Seed Quality, Too!

Cost of the seed itself is a minor part of the cost of producing a crop. Once planted, it costs just as much to produce and harvest a poor crop as a good one. It\u27s part of good management to start with high-quality seed

Are JCT Analyses of Tax Change Proposals Useful to Individual Taxpayers?

This article examines whether taxpayers may rely on Joint Committee of Taxation (JCT) studies to assess how a proposed tax change will impact their circumstances by evaluating the impact of a proposed tax law change to broaden the individual income tax base and lower individual income tax rates by performing a microeconomic analysis on their explicit tax burdens before and after the proposed change in tax law. Our results indicate that JCT studies do not fully reveal the impact of proposed tax law changes on individual explicit tax burdens. Finally, we provide a simple methodology to determine the distributional impact of tax proposals on individuals using publically available information

Phonon-assisted optical absorption in silicon from first principles

The phonon-assisted interband optical absorption spectrum of silicon is calculated at the quasiparticle level entirely from first principles. We make use of the Wannier interpolation formalism to determine the quasiparticle energies, as well as the optical transition and electron-phonon coupling matrix elements, on fine grids in the Brillouin zone. The calculated spectrum near the onset of indirect absorption is in very good agreement with experimental measurements for a range of temperatures. Moreover, our method can accurately determine the optical absorption spectrum of silicon in the visible range, an important process for optoelectronic and photovoltaic applications that cannot be addressed with simple models. The computational formalism is quite general and can be used to understand the phonon-assisted absorption processes in general

Knowledge, Beliefs, and Attitudes of Dental and Dental Hygiene Students Toward Obesity

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153645/1/jddj0022033720056912tb04032x.pd