Quantum Mechanical Single Molecule Partition Function from Path Integral Monte Carlo Simulations (open access)

Quantum Mechanical Single Molecule Partition Function from Path Integral Monte Carlo Simulations

An algorithm for calculating the partition function of a molecule with the path integral Monte Carlo method is presented. Staged thermodynamic perturbation with respect to a reference harmonic potential is utilized to evaluate the ratio of partition functions. Parallel tempering and a new Monte Carlo estimator for the ratio of partition functions are implemented here to achieve well converged simulations that give an accuracy of 0.04 kcal/mol in the reported free energies. The method is applied to various test systems, including a catalytic system composed of 18 atoms. Absolute free energies calculated by this method lead to corrections as large as 2.6 kcal/mol at 300 K for some of the examples presented.
Date: October 1, 2006
Creator: Chempath, Shaji; Bell, Alexis T. & Predescu, Cristian
Object Type: Article
System: The UNT Digital Library
Germanium-Based Detectors for Gamma-Ray Imaging andSpectroscopy (open access)

Germanium-Based Detectors for Gamma-Ray Imaging andSpectroscopy

Germanium-based detectors are the standard technology usedfor gamma-ray spectroscopy when high efficiency and excellent energyresolution are desired. By dividing the electrical contacts on thesedetectors into segments, the locations of the gamma-ray interactionevents within the detectors can be determined as well as the depositedenergies. This enables simultaneous gamma-ray imaging and spectroscopyand leads to applications in the areas of astronomy, nuclear physics,environmental remediation, nuclear nonproliferation, and homelandsecurity. Producing the fine-pitched electrode segmentation oftenrequired for imaging has been problematic in the past. To address thisissue, we have developed an amorphous-semiconductor contact technology.Using this technology, fully passivated detectors with closely spacedcontacts can be produced using a simple fabrication process. The currentstate of the amorphous-semiconductor contact technology and thechallenges that remain will be given in this paper.
Date: October 13, 2006
Creator: Amman, Mark; Luke, Paul N. & Boggs, Steven E.
Object Type: Article
System: The UNT Digital Library
Remaining Sites Verification Package for the 128-F-3 PNL Burn Pit, Waste Site Reclassification Form 2006-042 (open access)

Remaining Sites Verification Package for the 128-F-3 PNL Burn Pit, Waste Site Reclassification Form 2006-042

The 128-F-3 waste site is a former burn pit associated with the 100-F Area experimental animal farm. The site was overlain by coal ash associated with the 126-F-1 waste site and could not be located during confirmatory site evaluation. Therefore, a housekeeping action was performed to remove the coal ash potentially obscuring residual burn pit features. The results of verification sampling demonstrated that residual contaminant concentrations do not preclude any future uses and allow for unrestricted use of shallow zone soils. The results also showed that residual contaminant concentrations are protective of groundwater and the Columbia River.
Date: October 20, 2006
Creator: Dittmer, L. M.
Object Type: Report
System: The UNT Digital Library
Structure of incommensurate gold sulfide monolayer on Au(111) (open access)

Structure of incommensurate gold sulfide monolayer on Au(111)

Two-dimensional confined systems, such as substrate-supported incommensurate layers, are of interest because their structural and electronic properties may differ from those of bulk materials. While advances in experimental techniques have resulted in the growth of many such interesting systems, progress can often be hampered by the lack of an atomistic-scale understanding of the structure, especially for incommensurate systems. In this work, we develop an atomic-scale model for an ordered incommensurate gold-sulfide (AuS) adlayer that has been previously demonstrated to exist on the Au(111) surface, following sulfur deposition and annealing to 450 K. We introduce theoretical techniques within density functional theory to take into account charge transfer in an incommensurate system and model scanning tunneling microscopy images, which are in good agreement with experiment. Our simulations indicate that this model is remarkably robust. We analyze the nature of bonding in this structure using state-of-the-art Wannier-function based techniques. Our analysis provides a natural explanation for the extraordinary robustness and unusual stoichiometry of this layer. This structure and its chemistry have implications for related S-Au interfaces, such as those in self-assembled monolayers of thiols on Au substrates.
Date: October 4, 2006
Creator: Quek, S Y; Biener, M M; Biener, J; Bhattacharjee, J; Friend, C M; Waghmare, U V et al.
Object Type: Article
System: The UNT Digital Library
Power Corrections in Charmless Nonleptonic B Decays: Annihilationis Factorizable and Real (open access)

Power Corrections in Charmless Nonleptonic B Decays: Annihilationis Factorizable and Real

We classify {Lambda}{sub QCD}/m{sub b} power corrections to nonleptonic B {yields} M{sub 1}M{sub 2} decays, where M{sub 1,2} are charmless non-isosinglet mesons. Using recent developments in soft-collinear effective theory, we prove that the leading contributions to annihilation amplitudes of order {alpha}{sub s}(m{sub b}) {Lambda}{sub QCD}/m{sub b} are real. The leading annihilation amplitudes depend on twist-2 and the twist-3 three parton distributions. A complex nonperturbative parameter from annihilation first appears at {Omega}[{alpha}{sub s}{sup 2}({radical}{Lambda}m{sub b}){Lambda}{sub QCD}/m{sub b}]. 'Chirally enhanced' contributions are also factorizable and real at lowest order. Thus, incalculable strong phases are suppressed in annihilation amplitudes, unless the {alpha}{sub s}({radical}{Lambda}m{sub b}) expansion breaks down. Modeling the distribution functions, we find that (11 {+-} 9)% and (15 {+-} 11)% of the absolute values of the measured {bar B}{sup 0} {yields} K{sup -}{pi}{sup +} and B{sup -} {yields} K{sup -}K{sup 0} penguin amplitudes come from annihilation. This is consistent with the expected size of power corrections.
Date: October 10, 2006
Creator: Arnesen, Christian M.; Ligeti, Zoltan; Rothstein, Ira Z. & Stewart, Iain W.
Object Type: Article
System: The UNT Digital Library
The Development of New User Research Capabilities in Environmental Molecular Science: Workshop Report (open access)

The Development of New User Research Capabilities in Environmental Molecular Science: Workshop Report

On August 1, and 2, 2006, 104 scientists representing 40 institutions including 24 Universities and 5 National Laboratories gathered at the W.R. Wiley Environmental Molecular Sciences Laboratory, a National scientific user facility, to outline important science challenges for the next decade and identify major capabilities needed to pursue advanced research in the environmental molecular sciences. EMSL’s four science themes served as the framework for the workshop. The four science themes are 1) Biological Interactions and Interfaces, 2) Geochemistry/Biogeochemistry and Surface Science, 3) Atmospheric Aerosol Chemistry, and 4) Science of Interfacial Phenomena.
Date: October 31, 2006
Creator: Felmy, Andrew R.; Baer, Donald R.; Fredrickson, Jim K.; Gephart, Roy E. & Rosso, Kevin M.
Object Type: Report
System: The UNT Digital Library
Shillapoo Wildlife Area, Annual Report 2006-2007. (open access)

Shillapoo Wildlife Area, Annual Report 2006-2007.

This report summarizes accomplishments, challenges and successes on WDFW's Shillapoo Wildlife Area funded under Bonneville Power Administration's (BPA) Wildlife Mitigation Program (BPA project No.2003-012-00) during the Fiscal Year 07 contract period October 1, 2006-September 30, 2007. The information presented here is intended to supplement that contained in BPA's PISCES contract development and reporting system. The organization below is by broad categories of work but references are made to individual work elements in the PISCES Statement of Work as appropriate. The greatest success realized during this contract period was significant positive changes in the vegetative community in several wetland basins throughout the wildlife area. This major goal is being achieved in part by new equipment and operation capability funded under the BPA contract, state capital and migratory bird stamp funds, and the past or ongoing investment of other partners including Ducks Unlimited, The Natural Resources Conservation Service (NRCS), Clark Public Utilities and others. We continue to be challenged by requirements under the archaeological and historic preservation act necessary to protect many sensitive sites known to occur within the wildlife area. The problems encountered to date have been largely administrative in nature and those experienced this year were unforeseen and probably unavoidable. …
Date: October 1, 2006
Creator: Calkins, Brian
Object Type: Report
System: The UNT Digital Library
Mitochondrial Avid Radioprobes. Preparation and Evaluation of7'(Z)-[125I]Iodorotenone and 7'(Z)-[125I]Iodorotenol (open access)

Mitochondrial Avid Radioprobes. Preparation and Evaluation of7'(Z)-[125I]Iodorotenone and 7'(Z)-[125I]Iodorotenol

None
Date: October 18, 2006
Creator: VanBrocklin, Henry F.; Hanrahan, Stephen M.; Enas, Joel D.; Nandanan, Erathodiyil & O'Neil, James P.
Object Type: Article
System: The UNT Digital Library
Save Energy Now (open access)

Save Energy Now

This DOE Industrial Technologies Program brochure informs industry about Phase 2 of Save Energy Now, part of "Easy Ways to Save Energy," a national campaign to save energy and ensure energy security.
Date: October 1, 2006
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Precision cosmology and the landscape (open access)

Precision cosmology and the landscape

After reviewing the cosmological constant problem -- why is Lambda not huge? -- I outline the two basic approaches that had emerged by the late 1980s, and note that each made a clear prediction. Precision cosmological experiments now indicate that the cosmological constant is nonzero. This result strongly favors the environmental approach, in which vacuum energy can vary discretely among widely separated regions in the universe. The need to explain this variation from first principles constitutes an observational constraint on fundamental theory. I review arguments that string theory satisfies this constraint, as it contains a dense discretuum of metastable vacua. The enormous landscape of vacua calls for novel, statistical methods of deriving predictions, and it prompts us to reexamine our description of spacetime on the largest scales. I discuss the effects of cosmological dynamics, and I speculate that weighting vacua by their entropy production may allow for prior-free predictions that do not resort to explicitly anthropic arguments.
Date: October 1, 2006
Creator: Bousso, Raphael & Bousso, Raphael
Object Type: Article
System: The UNT Digital Library
Toward a Mesoscale Model for the Dynamics of Polymer Solutions (open access)

Toward a Mesoscale Model for the Dynamics of Polymer Solutions

To model entire microfluidic systems containing solvated polymers we argue that it is necessary to have a numerical stability constraint governed only by the advective CFL condition. Advancements in the treatment of Kramers bead-rod polymer models are presented to enable tightly-coupled fluid-particle algorithms in the context of system-level modeling.
Date: October 2, 2006
Creator: Miller, G H & Trebotich, D
Object Type: Article
System: The UNT Digital Library
Geometrically induced metastability and holography (open access)

Geometrically induced metastability and holography

We construct metastable configurations of branes and anti-branes wrapping 2-spheres inside local Calabi-Yau manifolds and study their large N duals. These duals are Calabi-Yau manifolds in which the wrapped 2-spheres have been replaced by 3-spheres with flux through them, and supersymmetry is spontaneously broken. The geometry of the non-supersymmetric vacuum is exactly calculable to all orders of the't Hooft parameter, and to the leading order in 1/N. The computation utilizes the same matrix model techniques that were used in the supersymmetric context. This provides a novel mechanism for breaking supersymmetry in the context of flux compactifications.
Date: October 23, 2006
Creator: Aganagic, Mina; Aganagic, Mina; Beem, Christopher; Seo, Jihye & Vafa, Cumrun
Object Type: Article
System: The UNT Digital Library
Cracking and Corrosion of Composite Tubes in Black Liquor Recovery Boiler Primary Air Ports (open access)

Cracking and Corrosion of Composite Tubes in Black Liquor Recovery Boiler Primary Air Ports

None
Date: October 31, 2006
Creator: Keiser, J. R.; Singbeil, D. L.; Sarma, G. B.; Kish, J. R.; Yuan, J.; Frederick, L. A. et al.
Object Type: Report
System: The UNT Digital Library
On the electronic configuration in Pu: spectroscopy and theory (open access)

On the electronic configuration in Pu: spectroscopy and theory

Photoelectron spectroscopy, synchrotron-radiation-based x-ray absorption, electron energy-loss spectroscopy, and density-functional calculations within the mixed-level and magnetic models, together with canonical band theory have been used to study the electron configuration in Pu. These methods suggest a 5f{sup n} configuration for Pu of 5 {le} n < 6, with n {ne} 6, contrary to what has recently been suggested in several publications. We show that the n = 6 picture is inconsistent with the usual interpretation of photoemission and x-ray absorption spectra. Instead, these spectra support the traditional conjecture of a 5f{sup 5} configuration in Pu as is obtained by density-functional theory. We further argue, based on 5f-band filling, that an n = 6 hypothesis is incompatible with the position of Pu in the actinide series and its monoclinic ground-state phase.
Date: October 11, 2006
Creator: Tobin, J G; Soderlind, P; Landa, A; Moore, K T; Schwartz, A J; Chung, B W et al.
Object Type: Article
System: The UNT Digital Library
CRD Report, October 2007 (open access)

CRD Report, October 2007

A review of various projects undertaken by Lawrence Berkeley National Laboratory's Computational Research Division.
Date: October 30, 2006
Creator: Wang, Ucilia
Object Type: Report
System: The UNT Digital Library
PASSIVITY BREAKDOWN AND EVOLUTION OF LOCALIZED CORROSION ON TYPE 316L STAINLESS STEEL (open access)

PASSIVITY BREAKDOWN AND EVOLUTION OF LOCALIZED CORROSION ON TYPE 316L STAINLESS STEEL

Passivity breakdown of 316L SS in the presence of aggressive Cl{sup -} and inhibitive NO{sub 3}{sup -} anions has been experimentally studied and the results have been interpreted in terms of the Point Defect Model (PDM). By introducing the competitive adsorption of Cl{sup -} and NO{sub 3}{sup -} into surface oxygen vacancies at the passive film/solution interface, the PDM yields a critical breakdown potential (V{sub c}) that is predicted to vary linearly with log[Cl{sup -}], or with log ([Cl{sup -}]/[NO{sub 3}{sup -}]) [1] when nitrate ions are present, which is shown in Fig. 1. The Point Defect Model also explains the fact that the slope of V{sub c} vs. log[Cl{sup -}] does not change in the presence of NO{sub 3}{sup -}, which is attributed to the quasi-equilibrium ejection of a cation from the barrier layer to form the vacancy pair V{sub M}V{sub O}{sup (2-{chi})} at the barrier layer/solution interface. The Point Defect Model predicts that measured V{sub c} increases linearly with the square root of voltage scan rate {nu}{sup 1/2} [1]. From this correlation, the critical, areal concentration of cation vacancies at the metal/barrier layer interface, {zeta}, has been estimated and found to be comparable to that calculated from the …
Date: October 23, 2006
Creator: S. Yang, G. Engelhardt, and D. D. Macdonald
Object Type: Article
System: The UNT Digital Library
Renewable Energy Development on Tribal Lands (open access)

Renewable Energy Development on Tribal Lands

Brochure describes the Tribal Energy Program, which provides American Indian tribes with financial and technical assistance for developing renewable energy projects on tribal land.
Date: October 1, 2006
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Linear Scaling 3D Fragment Method for Large-Scale ElectronicStructure Calculations (open access)

Linear Scaling 3D Fragment Method for Large-Scale ElectronicStructure Calculations

We present a linear scaling 3 dimensional fragment (LS3DF)method that uses a novel decomposition and patching scheme to do abinitio density functional theory (DFT) calculations for large systems.This method cancels out the artificial boundary effects that arise fromthe spatial decomposition. As a result, the LS3DF results are essentiallythe same as the original full-system DFT results with errors smaller thanthe errors introduced by other sources of numerical approximations. Inaddition, the resulting computational times are thousands of timessmaller than conventional DFT methods, making calculations with 100,000atom systems possible. The LS3DF method is applicable to insulator andsemiconductor systems, which covers a current gap in the DOE's materialsscience code portfolio for large-scale ab initio simulations.
Date: October 16, 2006
Creator: Wang, Lin-Wang; Zhao, Zhengji & Meza, Juan
Object Type: Report
System: The UNT Digital Library
Computing Criticality of Lines in Power Systems (open access)

Computing Criticality of Lines in Power Systems

We propose a computationally efficient method based onnonlinear optimization to identify critical lines, failure of which cancause severe blackouts. Our method computes criticality measure for alllines at a time, as opposed to detecting a single vulnerability,providing a global view of the system. This information on criticality oflines can be used to identify multiple contingencies by selectivelyexploring multiple combinations of broken lines. The effectiveness of ourmethod is demonstrated on the IEEE 30 and 118 bus systems, where we canvery quickly detect the most critical lines in the system and identifysevere multiple contingencies.
Date: October 13, 2006
Creator: Pinar, Ali; Reichert, Adam & Lesieutre, Bernard
Object Type: Article
System: The UNT Digital Library
Design and Application of an Electronic Logbook for Space System Integration and Test Operations (open access)

Design and Application of an Electronic Logbook for Space System Integration and Test Operations

In the highly technological aerospace world paper is still widely used to document space system integration and test (I&T) operations. E-Logbook is a new technology designed to substitute the most commonly used paper logbooks in space system I&T, such as the connector mate/demate logbook, the flight hardware and flight software component installation logbook, the material mix record logbook and the electronic ground support equipment validation logbook. It also includes new logbook concepts, such as the shift logbook, which optimizes management oversight and the shift hand-over process, and the configuration logbook, which instantly reports on the global I&T state of the space system before major test events or project reviews. The design of E-Logbook focuses not only on a reliable and efficient relational database, but also on an ergonomic human-computer interactive (HCI) system that can help reduce human error and improve I&T management and oversight overall. E-Logbook has been used for the I&T operation of the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) at the Stanford Linear Accelerator Center (SLAC). More than 41,000 records have been created for the different I&T logbooks, with no data having been corrupted or critically lost. 94% of the operators and 100% of …
Date: October 10, 2006
Creator: Kavelaars, Alicia T. & /SLAC /Stanford U., Dept. Aeronaut. Astronaut.
Object Type: Report
System: The UNT Digital Library
Final Report for OJI grant. (open access)

Final Report for OJI grant.

This document is a final report for DOE grant DE-FG02-00ER41147. The research described herein was funded in large part by this grant with additional support from the National Science Foundation. The primary focus of Averett's research effort is centered around the polarized {sup 3}He target in Hall A at Jefferson Lab. The close proximity of the College of William and Mary to Jefferson Lab has provided an outstanding opportunity to maintain a very active research program which still satisfying the demands of the college. Our research group includes four faculty, two post-doctoral fellows and eight graduate students. Averett also maintains a fully functional polarized {sup 3}e target lab at William and Mary which allows him to support the research program at Jefferson Lab while also doing research on polarized targets themselves. Since 1998, seven experiments using polarized {sup 3}He have been completed by the Jefferson Lab Hall A Polarized {sup 3}He Collaboration. Ten publications have been produced on this research and analysis of the two most recently completed experiments is underway. A description of the recent experiments and results is given below. In addition to target expertise, Averett has remained one of the most active collaborators in the data analysis …
Date: October 13, 2006
Creator: Averett, Todd
Object Type: Report
System: The UNT Digital Library
Effects of Biodiesel Blends on Vehicle Emissions: Fiscal Year 2006 Annual Operating Plan Milestone 10.4 (open access)

Effects of Biodiesel Blends on Vehicle Emissions: Fiscal Year 2006 Annual Operating Plan Milestone 10.4

The objective was to determine if testing entire vehicles, vs. just the engines, on a heavy-duty chassis dynamometer provides a better, measurement of the impact of B20 on emissions.
Date: October 1, 2006
Creator: McCormick, R. L.; Williams, A.; Ireland, J. & Hayes, R. R.
Object Type: Report
System: The UNT Digital Library
Exploring nanomagnetism with soft x-ray microscopy (open access)

Exploring nanomagnetism with soft x-ray microscopy

Magnetic soft X-ray microscopy images magnetism in nanoscale systems with a spatial resolution down to 15nm provided by state-of-the-art Fresnel zone plate optics. X-ray magnetic circular dichroism (X-MCD) is used as element-specific magnetic contrast mechanism similar to photoemission electron microscopy (PEEM), however, with volume sensitivity and the ability to record the images in varying applied magnetic fields which allows to study magnetization reversal processes at fundamental length scales. Utilizing a stroboscopic pump-probe scheme one can investigate fast spin dynamics with a time resolution down to 70 ps which gives access to precessional and relaxation phenomena as well as spin torque driven domain wall dynamics in nanoscale systems. Current developments in zone plate optics aim for a spatial resolution towards 10nm and at next generation X-ray sources a time resolution in the fsec regime can be envisioned.
Date: October 30, 2006
Creator: Fischer, P.; Kim, D. H.; Mesler, B. L.; Chao, W.; Sakdinawat,A. E. & Anderson, E. H.
Object Type: Article
System: The UNT Digital Library
Microbial Impacts on the Migration of Actinides -Effects of Exudates on Adsorption- (open access)

Microbial Impacts on the Migration of Actinides -Effects of Exudates on Adsorption-

The interaction of actinides with microorganisms has been extensively studied to elucidate migration behavior of actinides in the environments. However, the mechanisms of interaction of microorganisms and actinides are poorly understood. They have been conducting basic science on microbial accumulation of actinides in order to elucidate the environmental behavior of actinides under relevant conditions. The effect of exudates from bacteria cells on the sorption of Eu(III) and Cm(III) by Chlorella vulgaris was studied by a batch method. The pH dependence of log K{sub d} of Eu(III) and Cm(III) for cellulose, major component of C. vulgaris cell, differed from that for C. vulgaris. On the contrary, log K{sub d} of Eu(III) and Cm(III) for cellulose in the solution containing exudates from C. vulgaris cells in a 0.5% NaCl solution showed a similar pH dependence to that by C. vulgaris. These results strongly suggested that exudates affect on the sorption of Eu(III) and Cm(III) on C. vulgaris. Effect of desferrioxamine B (DFO), one of exudates to chelate the insoluble Fe(III), on the sorption of Pu(IV), Th(IV) and Eu(III) by Pseudomonas fluorescens was studied. In the presence of DFO the sorption of Pu(IV), Th(IV) and Eu(III) on the cells increased with a decrease …
Date: October 18, 2006
Creator: Ohnuki, T.; Ozaki, T.; Yoshida, T.; Nankawa, T.; Kozai, N.; Sakamoto, F. et al.
Object Type: Article
System: The UNT Digital Library