United States Department of Energy

About: United States Department of Energy is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Catalysis & Coal. The organization has 13656 authors who have published 14177 publications receiving 556962 citations. The organization is also known as: DOE & Department of Energy.

Determination of diabatic states through enforcement of configurational uniformity

Abstract: . An electronic structure-based construction of diabatic states from adiabatic states is formulated that is applicable when individual diabatic states contain several dominant configurations. It is accomplished by maximizing the electronic uniformity of the diabatic states with respect to their dominant configurations throughout the entire nuclear coordinate region. The configurations are generated from unambiguously defined diabatization-adapted molecular orbitals. The orthogonal transformation from adiabatic to diabatic states is deduced by an intrinsic analysis of the adiabatic CI coefficients, without calculating matrix elements of additional, derivative or non-derivative operators. The practicality of the method is demonstrated by applying it to the conical intersection region of the 11 A 1 and 21 A 1 states of ozone.

A Simple and Universal Gel Permeation Chromatography Technique for Precise Molecular Weight Characterization of Well-Defined Poly(ionic liquid)s

Abstract: Poly(ionic liquid)s (PILs) are an important class of technologically relevant materials. However, characterization of well-defined polyionic materials remains a challenge. Herein, we have developed a simple and versatile gel permeation chromatography (GPC) methodology for molecular weight (MW) characterization of PILs with a variety of anions. PILs with narrow MW distributions were synthesized via atom transfer radical polymerization, and the MWs obtained from GPC were further confirmed via nuclear magnetic resonance end group analysis.

Is the distribution grid ready to accept large-scale photovoltaic deployment? State of the art, progress, and future prospects

Abstract: The installed capacity of photovoltaic (PV) systems has recently increased at a much faster rate than the development of grid codes to effectively and efficiently manage high penetrations of PV within the distribution system. In a number of countries, PV penetrations in some regions are now raising growing concerns regarding integration. Management strategies vary considerably by country—some still have an approach that PV systems should behave as passive as possible, whereas others demand an active participation in grid control. This variety of grid codes also causes challenges in learning from “best practice.” This paper provides a review of current grid codes in some countries with high PV penetrations. In addition, the paper presents a number of country-specific case studies on different approaches for improved integration of PV systems in the distribution grid. In particular, we consider integration approaches using active and reactive power control that can reduce or defer expensive grid reinforcement while supporting higher PV penetrations. Copyright © 2011 John Wiley & Sons, Ltd.

Remarkable effects of disorder on superconductivity of single atomic layers of lead on silicon

Abstract: In bulk materials, superconductivity is remarkably robust with respect to non-magnetic disorder. In the two-dimensional limit, however, disorder and electron correlations both tend to destroy the quantum condensate. Here we study, both experimentally and theoretically, the effect of structural disorder on the local spectral response of crystalline superconducting monolayers of lead on silicon. In a direct scanning tunnelling microscopy measurement, we reveal how the local superconducting spectra lose their conventional character and show variations at scales significantly shorter than the coherence length. We demonstrate that the precise atomic organization determines the robustness of the superconducting order with respect to structural defects, such as single atomic steps, which may disrupt superconductivity and act as native Josephson barriers. We expect that our results will improve the understanding of microscopic processes in surface and interface superconductivity, and will open a new way of engineering atomic-scale superconducting quantum devices.