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Atomistic Modeling of Corrosion Accelerants in the Petroleum Industry
Project Lead: Christopher Taylor
Project Lead Institution: Los Alamos National Laboratory
Abstract
Materials selection is critical to petroleum refining operations, due to the frequently aggressive chemical, flow and thermal conditions encountered by structural components such as pipelines and condenser units. Chlorides, which cause pitting, sulfides, which cause uniform corrosion, and cyanides, which complex with iron, are commonly found in process stream wastewater, and their combination, along with other species, frequently confounds the process of materials selection. Chemical modification of process streams, such as addition of ammonium polysulfide, can help lower corrosion rates. However, the fundamental mechanisms of many of these corrosion processes remain unknown, thus limiting the determination of rational design principles. We propose to utilize the high performance computing resources (150,000 cpu hours) provided by the Chinook cluster at PNNL to calculate fundamental surface adsorption energies relevant to corrosion in the petroleum industry, particularly focusing upon the problem of the acceleration of sulfide corrosion of mild-steels by small quantities of cyanide.
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The Theoretical and Computational Analysis of Core-Level Spectroscopies
Project Lead: Paul Bagus
Project Lead Institution: University of North Texas
Abstract
Understanding the electronic structure and the chemical bonding of materials is critical in order to be able to relate the properties of these materials to their origins in the chemistry and physics of the systems. The core-level spectroscopies of X-Ray photoemission, XPS, and X-Ray absorption near edge structure, XANES, are regularly used to probe and characterize this electronic structure. From the XPS spectra, there is information on oxidation states, bonding, and environment. The XANES spectra provide additional and complimentary information about bonding and bond geometries as well as about the relative importance of spin-orbit coupling compared to ligand field effects. The analysis of core level spectroscopies in order to obtain information about materials properties are of direct and immediate interest for several projects within EMSL. However, in order to make effective use of the information contained in XPS and XANES measurements and to correctly infer materials properties from the core-level spectra, it is very important to have information from theoretical simulations of the spectra. This is where the partnership of the UNT and EMSL teams will be immensely productive. The EMSL team, under the leadership of Bert de Jong, has extensive experience with the calculation of electronic structure. On the other hand, the UNT team, lead by Professors Bagus and Wilson, brings complimentary expertise that is necessary for calculations of the properties of core-level excited and ionized states. We have developed, tested, and applied programs that are uniquely able to provide reliable simulations of XPS and XANES spectra. However, a major need is to place our existing, proof of concept, programs and methods on a supported platform, to make them widely accessible, and to make their use much more user friendly. Here the partnership between UNT and EMSL is critical. Furthermore, the applications of our methods to problems of interest within EMSL will establish a new level of computational power in this discipline. Our objective for the proposed EMSL partnership is to develop and make available, within EMSL, a powerful computational and theoretical tool for the analysis of the XPS and XANES spectra directly related to the research missions of EMSL.
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Exploring the Radiation Damage Resistance of Nanoscale Interfaces
Project Lead: Richard Kurtz
Project Lead Institution: Pacific Northwest National Laboratory
Abstract
The objective of this research is to rigorously test the hypothesis that internal interfaces can be manipulated at the nanoscale to enhance recombination of radiation-produced defects to dramatically reduce radiation damage without compromising other physical and mechanical properties. This hypothesis has never been rigorously tested and there has never been a fundamental study of radiation damage at interfaces that encompasses the wide range of interface types and structures proposed here. In this project we seek to 1) understand defect absorption at interfaces as a function of interface character and properties, 2) determine interface ability to adsorb and delocalize defects to promote recombination, and 3) determine interface stability and evolution under irradiation, including the saturation limit for defect absorption. This proposal is aligned with two of the principal focus areas within the Materials Sciences and Engineering Division of BES; including exploration of approaches to improve materials performance through interfacial design, and investigation of radiation effects on the mechanical and physical behavior of materials. The work consists of integrated experiments and modeling of a wide range of interface types to determine how variation in interface properties can affect defect absorption and recombination. Precisely tailored interfaces as well as nanostructured polycrystalline thin films will be studied in order to explore the full range of interface types relevant to the materials found in advanced nuclear energy systems. Reaching these objectives will demonstrate the stated hypothesis by determining interface stability under irradiation and will enable design of higher performance nuclear energy systems with attendant economic, safety and environmental benefits.
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Developing an Initial Framework for a Regional Earth System Model
Project Lead: Lai-Yung Ruby Leung
Project Lead Institution: Pacific Northwest National Laboratory
Abstract
Predicting climate change at the regional scale is critically important for assessing climate change impacts and developing strategies for mitigation and adaptation. Regional climate models (RCMs) have been used as a means for understanding regional climate processes and downscaling global climate simulations to provide insights on regional climate change and impacts. To date, most RCMs do not have the ability to simulate earth system processes such as sea ice, ocean, carbon and nitrogen cycle, and their interactions, which are essential for addressing a wide range of science questions including the complex interactions between aerosols, clouds, and sea ice and their influence on climate change in the Arctic, and terrestrial processes, carbon cycle feedbacks, and climate change. This proposal aims to implement a framework that will allow the Weather Research and Forecasting (WRF) model to adopt existing earth system model components from the Community Climate System Model (CCSM) through the CCSM flux coupler. This is an important first step that will open up research opportunities for using WRF as a regional earth system model and for enhancing the existing earth system model components for skillful simulations at the regional scale.
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The Role of Interfacial Processes on Mineral Transformations in Wet Supercritical CO2
Project Lead: Andrew Felmy
Project Lead Institution: Environmental Molecular Sciences Laboratory
Abstract
We propose a comprehensive experimental and theoretical investigation of the role of interfacial water and CO2 on the energies, mechanisms, and rates of reactivity of a series of orthosilicate and phyllosilicate minerals in contact with supercritical-CO2 (scCO2) containing variable H2O. The molecular mechanisms for carbonation reactions, as well as the distribution of H2O between scCO2 and mineral surfaces, will be followed using molecular simulations and surface spectroscopy as a function of T, P, mineral composition and structure, and aH2O. The dynamics of water reactivity will be simulated using newly developed molecular dynamics models and reaction barriers will be calculated using density functional and molecular orbital theory electronic structure methods. The theoretical studies will be coupled with high-resolution spectroscopic measurements (e.g., IR/FTIR, NMR) to investigate the formation and structure of water layers at mineral surfaces and in the interlayer region of phyllosilicates, and identify potential interfacial carbonate and silicate species. The macroscopic reactivity of the orthosilicates and the changes in interlayer water structure and reactivity of the phyllosilicates will be determined experimentally using high pressure cells. The proposed research will provide new insights into mineral transformations under extreme conditions and help establish a basis for assessing the effectiveness of CO2 sequestration in geologic disposal sites.
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Optical properties of silver nano-quantum-dots using long-range corrected TDDFT
Project Lead: Lasse Jensen
Project Lead Institution: Pennsylvania State University
Abstract
Strong fluorescence has been observed for small Ag and Au clusters encapsulated in organic dendrimers or peptide matrices. However, the chemical and physical properties of these small encapsulated nano-quantum-dots are rather poorly understood. The objective of this pilot project is to assess long-range corrected functionals for describing the optical properties of small metal clusters and mixed molecule-metal clusters. An important goal of this work is to assess new functionals that correctly describe low-lying CT transitions in these mixed metal-molecule systems. We have recently implemented long-range corrected functionals into NWChem, which will allow us to take full advantages of the high-performance computing facilities at EMSL.
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A Systems Biology Approach to Infectious Diseases Research
Project Lead: Joshua Adkins
Project Lead Institution: Pacific Northwest National Laboratory
Abstract
We describe an integrated program for coupling advanced capabilities in high-throughput transcriptomics, proteomics, and metabolomics with a comprehensive informatics infrastructure and a sophisticated approach to computational reconstruction and modeling of metabolic and gene regulatory networks. These powerful tools will be directed at delineating the mechanisms by which two related pathogens, Salmonella and Yersinia, adapt to the intracellular environment upon infecting macrophages and then manipulate that environment to facilitate their own survival and replication. The insights derived from modeling these behaviors may lead to the identification of novel therapeutic targets. The overall objectives are to: 1) Develop genome-scale metabolic and regulatory network reconstructions for Salmonella and Yersinia to provide the computational foundation for our systems biology approach; 2) Develop and disseminate 'sample matched' global datasets for Salmonella and Yersinia using transcriptomics, proteomics, and metabolomics technologies to provide the experimental foundation for our systems biology approach; 3) Produce and characterize knock-out mutations in regulatory genes predicted to be essential for systemic infection in mouse models for Salmonella enterica and Yersinia pestis; and 4) Use the network reconstructions, omics results, and phenotype changes in knock-out mutants to refine computational models of pathogenesis for Salmonella and Yersinia.
EMSL world class capabilities in proteomics, NMR for structure and metabolomics, and advanced computation are well recognized. While all of these areas are included in the proposal the real benefit of using EMSL's capabilities is the team oriented nature of the operations; the project described above requires multiple-disciplines and multiple-strategies. These capabilities with the high quality team are why we request to perform this research in collaboration with EMSL.
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Role of Microenvironments and Transition Zones in Subsurface Reactive Contaminant Transport
Project Lead: James Mckinley
Project Lead Institution: Pacific Northwest National Laboratory
Abstract
The PNNL Scientific Focus Area (SFA) will resolve critical Hanford and basic subsurface science issues through integrated, multi-disciplinary, science-theme focused research on the role of microenvironments and transition zones in the reactive transport of technetium (Tc), uranium (U), and plutonium (Pu). Microenvironments are small domains within larger ones that exert a disproportionate influence on subsurface contaminant migration. They may be internal fractures or microbiologic niches within porous media lithic fragments; grain coatings, bio-films, or micro-colonies on larger mineral particles; or compact silt/clay stringers in gravel-dominated subsurface sediments. Transition zones are field scale features where chemical, physical, or microbiologic properties change dramatically over relatively short distances (e.g., 1 m). They exhibit steep, transport-controlled gradients of system controlling chemical species such as O2, H+, or organic carbon. Microenvironments and transition zones frequently dominate subsurface contaminant reactivity, with strong effects resulting from the coupling of chemical reaction, physical transport (advection, diffusion), and microbiologic processes. Past EMSP and NABIR research has documented the importance of these zones at the Hanford site.
The overall ten-year goals of the SFA are to develop: i.) an integrated conceptual model for microbial ecology in the Hanford subsurface and its influence on contaminant migration, ii.) a fundamental understanding of chemical reaction, biotransformation, and physical transport processes in microenvironments and transition zones, and iii.) quantitative biogeochemical reactive transport models for Tc, U, and Pu that integrate multi-process coupling at different spatial scales for field-scale application. Targeted contaminant chemical reaction and biotransformation processes include heterogeneous/biologic electron transfer, precipitation and dissolution, and surface complexation. The SFA will emphasize lab-based, coupled computational and experimental research using relevant physical/biologic models, and sediments and microbial isolates from various Hanford settings to explore
molecular, microscopic, and macroscopic processes underlying field-scale contaminant migration. It will also pursue the refinement of geophysical techniques to define, characterize, and map spatial structures and reactive transport properties of microenvironments and transition zones in the field. The SFA will partner with the PNNL Environmental Molecular Sciences Laboratory (EMSL) to develop molecular understandings of key processes, and the Hanford Integrated Field Challenge (IFC) for access to, and samples from subsurface environments where these zones exist and are important.
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Modeling defect- and interface-induced rapid decomposition of molecular materials
Project Lead: Maija Kukla
Project Lead Institution: University of Maryland, College Park
Abstract
The main goals of this study are: (1) to achieve first principles understanding of the structure and properties of basic defects in a wide class of molecular materials; (2) to develop a novel theoretical/computational method to describe defect- and deformation-induced chemistry and physics in molecular materials.
One of the important objectives of this proposal is to explore the recently developed state-of-the-art embedding methodology (GUESS), which has been implemented within the framework of the NWChem quantum chemistry package. We plan to use this capability, adjust it, as appropriate, and then apply it to study the electronic structure and dynamics of electronically excited states. It is assumed that these states may be trapped on the lattice imperfections and that they significantly modify physical and chemical properties of molecular materials.
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Electron and hole trapping and excitations in polycrystalline oxides: challenge for materials simulations
Project Lead: Alexander Shlyuger
Project Lead Institution: London, University College
Abstract
The objectives of this proposal are to investigate the applicability and effectiveness of NWChem-Guess embedding capability for studying the electronic properties and defect mobility in the nanocrystalline metal-oxide materials such as MgO, ZrO2 and HfO2. The main focus will be on the electronic properties of interfaces between nanocrystallites in these materials and how they are affected by processes such as electronic excitation or applied electric fields. Two types of nanocrystalline systems will be considered: polycrystalline films and nanopowders, and the calculations will be carried out in strong collaboration with the experimental work in the group of Dr Wayne Hess at PNNL. These calculations can be used to develop models for desorprtion, resistive switching, dielectric breakdown and radiation damage in nanocrystalline oxide films and for charge dynamics in oxide nanopowders which underpin numerous applications in electronics, catalysis and photonics.
