Capturing electronic correlations in electron-phonon interactions in molecular systems with the GW approximation

Electron-phonon interactions are of great importance to a variety of physical phenomena, and their accurate description is an important goal for first-principles calculations. Isolated examples of materials and molecular systems have emerged where electron-phonon coupling is enhanced over density functional theory (DFT) when using the Green's-function-based ab initio GW method, which provides a more accurate description of electronic correlations. It is however unclear how general this enhancement is, and how employing high-end quantum chemistry methods, which further improve the description of electronic correlations, might further alter electron-phonon interactions over GW or DFT. Here, we address these questions by computing the renormalization of the highest occupied molecular orbital energies of Thiel's set of organic molecules by harmonic vibrations using DFT, GW and equation-of-motion coupled-cluster calculations. We find that GW can increase the magnitude of the electron-phonon coupling across this set of molecules by an average factor of 1.1-1.8 compared to DFT, while equation-of-motion coupled-cluster leads to an increase of 1.4-2. The electron-phonon coupling predicted with the ab initio GW method is generally in much closer agreement to coupled cluster values compared to DFT, establishing GW as an accurate way of computing electron-phonon phenomena in molecules and beyond at a much lower computational cost than higher-end quantum chemistry techniques

Recent Developments: The Uniform Arbitration Act

This Article is an overview of recent court decisions that interpret state versions of the Uniform Arbitration Act ( U.A.A. ).\u27 Arbitration statutes patterned after the U.A.A. have been adopted by thirty-four states and the District of Columbia. The goal of this project is to promote uniformity in the interpretation of the U.A.A. by articulating the underlying policies and rationales of recent court decisions interpreting the U.A.A

Recent Developments: The Uniform Arbitration Act

This Article is an overview of recent court decisions that interpret state versions of the Uniform Arbitration Act ( U.A.A. ).\u27 Arbitration statutes patterned after the U.A.A. have been adopted by thirty-four states and the District of Columbia. The goal of this project is to promote uniformity in the interpretation of the U.A.A. by articulating the underlying policies and rationales of recent court decisions interpreting the U.A.A

Atmospheric Contributors to Heavy Rainfall Events in the Arkansas-Red River Basin

This study analyzed the top 1% 24-hour rainfall events from 1994 to 2013 at eight climatological sites that represent the east to west precipitation gradient across the Arkansas-Red River Basin in North America. A total of 131 cases were identified and subsequently classified on the synoptic-scale, mesoscale, and local-scale to compile a climatological analysis of these extreme, heavy rainfall events based on atmospheric forcings. For each location, the prominent midtropospheric pattern, mesoscale feature, and predetermined thermodynamic variables were used to classify each 1% rainfall event. Individual events were then compared with other cases throughout the basin. The most profound results were that the magnitudes of the thermodynamic variables such as convective available potential energy and precipitable water values were poor predictors of the amount of rainfall produced in these extreme events. Further, the mesoscale forcings had more of an impact during the warm season and for the westernmost locations, whereas synoptic forcings were extremely prevalent during the cold season at the easternmost locations in the basin. The implications of this research are aimed at improving the forecasting of heavy precipitation at individual weather forecasts offices within the basin through the identified patterns at various scales

Geriatrics Attitudes and Knowledge Among Surgical and Medical Subspecialty House Officers

To examine geriatrics knowledge and attitudes of non-primary care house officers (HOs) before and after a multidisciplinary faculty development program. DESIGN : Serial cross-sectional surveys. PARTICIPANTS : HOs. SETTING : A large midwestern academic medical center. INTERVENTION : Faculty from seven surgical and six medical subspecialties participated in weekly seminars for 9 months and implemented geriatrics curricula in their HO programs. MEASUREMENTS : HO geriatrics attitudes and knowledge were measured using the University of California at Los Angeles Geriatrics Attitudes Scale (GAS; 14 items), two scales of the Maxwell Sullivan test (Therapeutic Potential and Time/Energy; six items each; lower scores denote more-favorable attitudes), and the Geriatrics Clinical Knowledge Assessment (20 multiple choice items; range 0–100%). Repeat surveys were administered in seven disciplines after geriatrics curriculum implementation. RESULTS : Baseline (n=175) geriatrics attitudes were favorable (e.g., 3.7 for GAS; 2.1 for Time/Energy), with more-favorable attitudes among medical subspecialty than surgical HOs (e.g., mean GAS 3.8 and 3.6, respectively; P =.001), and with advanced training. Mean baseline knowledge scores were 65.1% among all HOs. No differences in attitudes or knowledge were observed between the first (n=100) and second (n=90) cohorts in the seven disciplines that administered subsequent tests. CONCLUSION : Geriatrics attitudes of non-primary care HOs are positive, and knowledge is moderate, suggesting need for and potential effect of geriatrics curricula. Demonstrating effects on learner outcomes of faculty development programs may require more than one faculty member per discipline and measures that are curriculum-specific and detailed rather than general and brief.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66180/1/j.1532-5415.2007.01475.x.pd

Mini-mast CSI testbed user's guide

The Mini-Mast testbed is a 20 m generic truss highly representative of future deployable trusses for space applications. It is fully instrumented for system identification and active vibrations control experiments and is used as a ground testbed at NASA-Langley. The facility has actuators and feedback sensors linked via fiber optic cables to the Advanced Real Time Simulation (ARTS) system, where user defined control laws are incorporated into generic controls software. The object of the facility is to conduct comprehensive active vibration control experiments on a dynamically realistic large space structure. A primary goal is to understand the practical effects of simplifying theoretical assumptions. This User's Guide describes the hardware and its primary components, the dynamic characteristics of the test article, the control law implementation process, and the necessary safeguards employed to protect the test article. Suggestions for a strawman controls experiment are also included

Flat branches and pressure amorphization

After summarizing the phenomenology of pressure amorphization (PA), we present a theory of PA based on the notion that one or more branches of the phonon spectrum soften and flatten with increasing pressure. The theory expresses the anharmonic dynamics of the flat branches in terms of local modes, represented by lattice Wannier functions, which are in turn used to construct an effective Hamiltonian. When the low-pressure structure becomes metastable with respect to the high-pressure equilibrium phase and the relevant branches are sufficiently flat, transformation into an amorphous phase is shown to be kinetically favored because of the exponentially large number of both amorphous phases and reaction pathways. In effect, the critical-size nucleus for the first-order phase transition is found to be reduced to a single unit cell, or nearly so. Random nucleation into symmetrically equivalent local configurations characteristic of the high-pressure structure is then shown to overwhelm any possible domain growth, and an ``amorphous'' structure results.Comment: 8 pages with 3 postscript figures embedded; Proceedings of the 4th International Discussion Meeting on Relaxations in Complex Systems, Hersonissos, Heraklion, Crete, June 16-23, ed. K. L. Ngai, Special Issues of the Journal of Non-Crystalline Solids, 200

Dopant effects on the photoluminescence of interstitial-related centers in ion implanted silicon

The dopant dependence of photoluminescence(PL) from interstitial-related centers formed by ion implantation and a subsequent anneal in the range 175–525 °C is presented. The evolution of these centers is strongly effected by interstitial-dopant clustering even in the low temperature regime. There is a significant decrease in the W line (1018.2 meV) PL intensity with increasing B concentration. However, an enhancement is also observed in a narrow fabrication window in samples implanted with either P or Ga. The annealtemperature at which the W line intensity is optimized is sensitive to the dopant concentration and type. Furthermore, dopants which are implanted but not activated prior to low temperature thermal processing are found to have a more detrimental effect on the resulting PL. Splitting of the X line (1039.8 meV) arising from implantation damage induced strain is also observed.This work is supported by a grant from the Australian Research Council. B.C.J. is partially supported by the Japan Society for the Promotion of Science (JSPS) (Grant-in-aid for Scientific Research, 22.00802)