September 2015 - Allocations-admins - mailman3.cels.anl.gov

New LCRC report submitted for anl-dcc
by support＠lcrc.anl.gov 07 Sep '15

07 Sep '15

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2015/?project=anl-dcc

1 0

[LCRC Accounts] Yearly Allocation Request for SnI4
by accounts＠lcrc.anl.gov 06 Sep '15

06 Sep '15

Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Michael Hu Project Name: SnI4 Division: XSD Project title: Modeling of the structure and vibrational dynamics of materials at High Pressure Associated funding: DOE and NSERC (Canada) Other Systems: Science: Electronic structure calculations are to be used to assist the assignments of vibrational density of states (VDOS) obtained from high pressure nuclear resonant inelastic x-ray scattering and diffraction experiments. Several phase transition systems will be studied with the combination of simulations and x-ray experiments done primarily at APS. Various experiments have revealed very interesting dynamic behavior on pressurization. The objective of the computational investigation is to elucidate the vibrational spectra and to reveal the mechanism of the PIA transformation. Although pressure-induced amorphization (PIA) has been observed in many solids, the true mechanism is elusive and remain a subject of debate and misinterpretation. Two scenarios have been proposed. In the first observation of this phenomenon in ice Ih , it was assumed the transition is akin to pseudomelting in which the crystalline solid crosses the extrapolated melting line by pressurization at low temperature. This suggests a possible thermodynamic connection between the amorphous state(s) to the liquid, and the prevalent but controversial “two-liquid” model for water is a consequence of this conjecture. Another proposal for PIA transition is that it is a mechanical process due to the instability of the crystal framework under compression and thus violates the Born stability conditions. Recent experiments have shown that in several materials that PIA believed to occur was found to bypass when compression was performed under quasi-hydrostatic conditions. Significant ly, archetypal example of ice Ih and SnI4, the subject of our focus, are two solids that no crystalline form was yet to be found in lieu of the disordered structure and the nature of the amorphous phases is still an open question. SnI4 offers several advantages for the characterization of PIA transformation. It is a solid at room temperature and has a fairly high melting point making it comparatively easy to handle as compared to Ice Ih. Project description: The principal project is on the understanding of the temperature and pressure dependent VDOS of the Sn atoms in SnI4 and the Fe and Eu atoms in FeEuAs associated with structural phase transformations. The objectives of this proposal are (i) to continue the study on the finite temperature effect on the vibration density of states of the Sn atoms in SnI4 to higher pressures; (ii) to start new calculation son the analogous SnBr4 in which experiments have been planned; (iii) to start new calculations on other systems under high pressures to studies their phase transition mechanisms. Our preliminary calculations have identified the PIA mechanism as mechanical instability, rather than pseudo-melting. A publication is in review. In SnI4, three consecutive transitions, viz. crystal -> crystal at 8 GPa, crystal -> amorphous at 14 GPa and a novel amorphous -> crystal at 60 GPa have been identified. First principles molecular dynamics calculations have been performed and the results reproduced the experimental observation. The mechanisms for the structural transformation have been characterized and shown to be due to mechanical instability of the respective precursor solid phases. For SnI4 studies, we have now more data at higher pressures, and we expect to perform new simulations to match the new data. In FeEuAs, the focus is to explain the dramatic changes in the Fe and Eu vibration density of states after the insulator -> metal transition at 6 GPa. In this case, the lattice dynamics were investigated with the supercell method. The aim is to compute the Fe and Eu vibrational density of states near the isostructural insulator -> metal phase transition. Although geometry optimizations of the unit cells completed successfully, severe SCF convergence problems were encountered in the supercell calculations. The computation is still underway. In collaboration with HPCAT, we have studied changes in the valence electron topology of single crystal of alpha-Ge under pressure at the vicinity of the alpha (fcc) -> beta (tetragonal) structure transition near 11 GPa. Analysis of the experimental diffraction data shows the emergence of significant d-orbital character in the chemical bond prior to the transition. Theoretically calculated charge density using two functionals, Wu-Cohen and PBE, only yield qualitatively agreement with experiment. The results suggest either a shortcoming in the density functionals or electron correlation effect may be important in this simple FCC Ge crystal. Recently, we have initiated a new investigation to correlation the structure vs composition relationships for the palladium/platinum element group (PEG) pentlandite minerals. Pentlandite occurs in terrestrial environments with an Fe/Ni ratio of around 0.5, however unusually high Fe pentlandite with an Fe/Ni ratio of 0.7 has been found in extraterrestrial meteorites. The goal of the project is to determine the optimal Fe/Ni stoichiometry, magnetic and electronic structure of pentlandite and to understand the underlying reason this mineral crystallizes with different compositions in terrestrial vs extraterrestrial environments. This work is still under way. First-principles methods static and dynamic calculations based on density functional approximation will be performed. The stability of the lattice in the ambient structure will be examined using finite temperature self-consistent lattice dynamics and molecular dynamics calculations. Specially, structural prediction using evolution algorithms (C. Glass and A. Oganov, J. Chem. Phys. 124, 244704 (2006); Y. Wang, J. Lv, L. Zhu and Y. Ma, Phys. Rev. B 82, 094116 (2010)) and constant pressure molecular dynamics calculations will be performed. The ambient fcc unit cell of SnI4 is consisted of 40 atoms. Any calculations using a supercell model will require exceeding 320 atoms. For this purpose, significant computational resource is required. The density functional codes to be used in this study are well maintained and proven highly-parallel public domain programs. The code Qbox will be used mainly for molecular dynamism calculations. Other codes such as SIESTA and VASP (one of the PI holds the license) will be used for static and properties calculations. Structural search will be performed using our own implementation of the evolution algorithm (Y. Yao, J.S. Tse and K. Tanaka, Phys. Rev. B 77, 052103 (2008)). Structural search and molecular dynamics calculations are computationally (both on the speed of the CPU and memory capacity) very demanding. Industry partnership: Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 499999 Q1: 99999 Q2: 120000 Q3: 140000 Q4: 140000 Justification: Storage requirements: Thank You, The LCRC Accounts System

1 0

[LCRC Accounts] Yearly Allocation Request for NE_RANS
by accounts＠lcrc.anl.gov 05 Sep '15

05 Sep '15

Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Prasad Vegendla Project Name: NE_RANS Division: NE Project title: RANS-based CFD for Nuclear Reactors Associated funding: DOE-NE, GTRI, CRADA-Cummins Other Systems: NE Division clusters Science: The commercial CFD code STAR-CCM+ (and its predecessor STAR-CD) have been employed at Argonne for nuclear reactor analysis for more than 10 years in a variety of applications. The objective is to predict the pressure, velocity and temperature distribution in nuclear reactor cores and coolant systems to ensure that the reactor is sufficiently cooled during normal operation and remains cool during postulated adverse events. Other design goals include minimizing the local peaks in power and temperature. The physics depends on the reactor and scenario being analyzed, but often includes turbulent flow, buoyancy-driven naturally circulating flows, conjugate heat transfer, and multiphase flows. In addition, the geometry is often quite complex, which requires computationally intensive mesh generation procedures. Project description: Anticipated CFD support of nuclear reactor analysis in FY16 includes: • Supporting NNSA’s efforts under the GTRI-Convert program to convert research reactors fueled with highly-enriched uranium to instead employ low-enriched uranium, and in doing so reduce the associated proliferation risk. Such reactor conversions require significant analysis to ensure that their cool ability under a range of conditions. Given the range of geometry and flow conditions presented by the various research reactors under consideration, a general-purpose thermofluid analysis capability—like CFD—is required. • Supporting advanced reactor systems modeling by coupling STAR-CCM+ to system codes for transient analysis of postulated adverse events, to ensure that the reactor remains cool even under highly unlikely multi-component failures. • Supporting advanced modeling and simulation efforts under the DOE-NE NEAMS program by integrating STAR-CCM+ into the SHARP reactor analysis package. By including STAR-CCM+ as an optional component in SHARP will provided needed flexibility and enhance the access for new users to the advanced modeling and simulation toolkit. • Support of design and safety analysis of sodium-cooled fast reactors for the DOE-NE Advanced Reactor Concepts program. • Verification and validation of STAR-CCM+ for nuclear rector analysis. • In work for others program, several STAR-CCM+ simulation runs are planned to optimize the aerodynamic and underhood thermal analysis of the heavy-duty vehicles. STAR-CCM+ has been employed by analysts in the Nuclear Engineering Division on LCRC clusters since its inception (both Jazz and Fusion), and has demonstrated good scalability up to several hundred cores. Recent simulations on 720 Fusion cores reported only 15% overhead associated with MPI communication. This project will be used by 5-10 STAR-CCM+ analysts in the NE Division. Industry partnership: Cummins Inc. Columbus, Indiana Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 1000000 Q1: 250000 Q2: 250000 Q3: 250000 Q4: 250000 Justification: STARCCM+ is a highly scalable tool on fusion. NE users demonstrated good scalability up to several hundred cores. Recent simulations on 720 Fusion cores reported only 15% overhead associated with MPI communication. Storage requirements: Thank You, The LCRC Accounts System

1 0

[LCRC Accounts] Yearly Allocation Request for CFD-TPM
by accounts＠lcrc.anl.gov 05 Sep '15

05 Sep '15

Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Prasad Vegendla Project Name: CFD-TPM Division: NE Project title: Computational Fluid Dynamics Modeling of Two-phase Boiling Flow and Critical Heat Flux Associated funding: Strategic-LDRD Other Systems: Science: Multi-phase flow and boiling are of fundamental importance in the design of nuclear reactors used for energy generation, the vast majority of which are cooled by water. These reactors, referred to as Light Water Reactors (LWRs), can be divided into two major types: the Boiling Water Reactors (BWR) designed to operate under saturated boiling conditions, and the Pressurized Water Reactors (PWR) designed to operate at higher pressure than the BWRs and under sub-cooled boiling conditions. The assessment of the fuel assembly behavior under two-phase flow conditions is of particular importance, since many design and safety criteria depend on it. In particular, boiling flows are subject to the phenomenon known as "boiling crisis" where, for high cladding surface heat fluxes (exceeding the critical heat flux or CHF), the heat transfer between the cladding and coolant deteriorates, leading to sharply higher cladding surface temperatures. Such temperatures lead to a deterior ation of cladding structural integrity and ultimately to fuel pin failure and radionuclide release. Therefore, the Nuclear Regulatory Commission requires vendors to accurately evaluate the CHF phenomenon in their nuclear reactor designs, and to demonstrate that the “boiling crisis” can be avoided in their reactors even under unlikely hypothetical accident scenarios. New fuel assembly designs need therefore to be tested in very expensive high-power, full-scale water loops, of which very few exist. • The main objective of this project is to build two-fluid boiling framework in the Nek5000 solver. As a first step, a homogeneous and drift-flux model successfully implemented, which will be used to validate more sophisticated approaches that will be developed later, including two-fluid modeling approaches. Project description: In boiling water reactors, dryout is an important limiting phenomenon in the design of heat exchangers and is associated with the disappearance of the liquid film on the wall in heat exchanger tube. A consequence of this non-wetting heated surface deteriorates the convective heat transfer mechanism resulting in a large rise in the wall temperature of heat flux imposed system such as nuclear reactor fuel rod assemblies. Since dryout is a hydrodynamic phenomenon involving entrainment and redeposition of droplets as well as boiling/evaporation of the liquid, the location of dryout is dynamic and its fluctuation may also give rise to thermal fatigue and corrosion. A large number of experimental and theoretical studies have been conducted over the past several decades to understand and quantify the processes leading to dryout in a heat exchanger tube. * Nek5000 is a highly-scalable open-source transient CFD code developed by MCS-Argonne National Laboratory. This code is based on spectral element method and it is written in basic FORTRAN and C languages. It has more than 200 users world-wide and a long history of development, verification, and validation. * In this project, Nek5000 is used as a platform to develop two-fluid model. * In order to validate the Nek5000 development for two-phase boiling capability, several simulation runs are planned for wide range of pressure, mass flux and wall heat flux. * In FY2015, blues allocated hours are efficiently used for projects of CFD-TPM, NE_RANS and SHARP-IF. * A total of 4 members can use the allocated hours Industry partnership: Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 800000 Q1: 200000 Q2: 200000 Q3: 200000 Q4: 200000 Justification: Nek5000 is a highly scalable tool on fusion. NE users demonstrated good scalability up to several hundred cores. Recent simulations of homogeneous two-fluid boiling model on Fusion cores reported 10% and 58% overhead associated with MPI communication for 128 and 256 cores, respectively. Storage requirements: Thank You, The LCRC Accounts System

1 0

New LCRC report submitted for entropy
by support＠lcrc.anl.gov 04 Sep '15

04 Sep '15

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2015/?project=entropy

1 0

New LCRC report submitted for entropy
by support＠lcrc.anl.gov 04 Sep '15

04 Sep '15

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2015/?project=entropy

1 0

[LCRC Accounts] Yearly Allocation Request for Redoxshuttles
by accounts＠lcrc.anl.gov 04 Sep '15

04 Sep '15

Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Paul Redfern Project Name: Redoxshuttles Division: MSD Project title: Redox Shuttles and Additives for Lithium-Ion Batteries Associated funding: EERE-DOE Other Systems: Small Group Cluster Science: There are several types of electrolytes that are used to improve the performance of the batteries. Some electrolyte additives are used to improve lithium-ion battery performance by facilitating solid-electrolyte (SEI) formation, reducing irreversible capacity and gas formation, improving thermal stability, protecting cathode materials, improving electrolyte properties, decreasing flammability and providing overcharge protection. It is also desirable to develop additives that can stabilize electrolytes near 5 V in order to deliver energy at higher density and potential. Numerous additives have been developed that improve some aspect of battery performance, but many introduce negative side effects. A second type is used to prevent dangerous overcharge of lithium-ion batteries occurs when charge from current forced through a cell exceeds its charge storing capability, leading to chemical and electrochemical reactions, rapid temperature rise, self accelerating reactions and explosion. Redox shuttle molecules are additives that are reversibly oxidized and reduced at potentials slightly higher than the end of charge cathode potential, locking the cathode potential at the oxidation potential of the redox shuttle and thereby preventing overcharging. The shuttling mechanism can be regarded as an internal short that can be repeated continuously due to reversible oxidation and reduction of the shuttle molecule. Redox shuttles with excellent performance and compatibility are critically important to the development of lithium-ion battery technology. Development of new redox shuttles is difficult and has been largely based on trial and error due to the multidisciplinary knowledge r equired. Ideal redox shuttles should be electrochemically reversible, have a redox potential slightly higher than the cathode end of charge potential, be electrochemically stable, have good solubility and high diffusion coefficients, and be compatible with the cell, i.e., they should not adversely affect normal cell performance. The shuttle should not react with electrolytes, the solid-electrolyte interface, separators, current collectors, binders, etc. Interface resistance and thermal properties should also be considered. Project description: Over the past year we have calculated solvation free energies of molecular LiO2 and Li2O2 in various solvents were calculated using various explicit and implicit solvent models, as well as ab initio molecular dynamics (AIMD) methods. Best estimates for the solvation energies from these calculations along with calculated lattice energies of Li2O2 and LiO2 were used to determine the solubility of bulk LiO2 and Li2O2. The solubility of LiO2 was found to be about 17 orders higher than that of Li2O2. The effect of finite crystal size of LiO2 and Li2O2 on the solubility was also considered and was found to increase the solubility, although LiO2 is still much more soluble. The difference in solubilities between LiO2 and Li2O2 will likely affect the growth mechanism and resulting morphologies of the products formed during battery discharge, affecting the performance of the battery cell. We also examined production of a lithium superoxide discharge product on the cathode in a Li-O2 battery. DFT was used to obtain values of material properties not available experimentally such as LiO2 solubility in DME and elastic properties of the particles. The mesoscale model predicts that coarsening, in which large particles grow and small ones disappear, has a substantial effect on the size distribution of the LiO2 particles during the discharge process. The size evolution during discharge is the result of an interplay between this coarsening process as well as growth. The growth through continued deposition of LiO2 has the effect of causing large particles to grow faster and delays the dissolution of small particles. The predicted size evolution is consistent with experimental results for a previously reported cathode material based on activated carbon during discharge and when it is at rest. The model, even without complex microstructure, can capture size and number of LiO2 particles, but not the shape, e.g. toroid formation. Best estimates fo r the LiO2 solvation energy from these calculations along with a calculated lattice energy of LiO2 were used to determine the solubility of bulk LiO2. The best estimate for the solubility of LiO2 is about 1 mM, although this has very large uncertainties because small differences in the calculated solvation energy leads to large differences in the solubility due to the exponential. For example, a difference of 2 kcal/mol in solvation energy translates to more than 2 orders of magnitude difference in solubility. The solvation energies are difficult to calculate even to 2 kcal/mol in accuracy. This value from density functional calculations is used initially in the model and subsequently a value for solubility is derived from fits to reproduce experimental data. The solubility from these fits is similar to that predicted from the DFT calculations. We intend to evaluate at least 200 electrolytes for Lithium-O2 batteries. The most important challenge in Lithium-Air battery research is finding stable non-aqueous electrolytes which permit reversible cycling of the cell. A solvent should have a high dielectric constant in order to dissolve Li+, low viscosity for fast Li+ transport, high stability, low vapor pressure, high oxygen solubility, high O2 and superoxide transport properties, and low toxicity. Solvents should partially dissolve lithium oxide species in order to reduce clogging and increase charge current rate. Quantum chemical calculations can help identify reaction pathways which affect reversibility. So far organic solvents such as ethers, amides, lactams, oxazolidinones, phosphorus compounds and nitriles have been screened for Lithium-Air batteries based on susceptibility to attack by superoxide anion and pKa. No correlation between simple molecular descriptors and activation free energies was found. Low electro philicity has also been used to identify potential candidates, since they would be less susceptible to attack by superoxide or other anion. Other solvents such as sulfones, sulfoxides and ionic liquids have been examined. Lithium salts like LiTFSI can decompose at the lithium electrode and the resulting CF3 radicals can abstract hydrogens from solvents like ethers. Hydrogens on carbons adjacent to heteroatoms (e.g. O, N, F) are more labile due to the anomeric effect. Superoxide anion can abstract protons from proton source impurities (e.g. water) leading to formation of the strong base HOO- via disproportionation which can then react as a nucleophile with the solvent. Superoxide was found not to react with TEGDME ether (Nazar). We will use hydrogen and proton abstraction from and nucleophilic attack by a strong base on the electrolyte along with advanced descriptors (e.g. Fukui functions, hardness and chemical potential) to screen for stable solvents. Oxygen reduction in the aprotic Li-O2 battery takes place at the boundary between the electrolyte and the cathode so oxygen must dissolve and diffuse in the electrolyte. Unfortunately, aprotic solvents are inadequate in this regard so oxygen enriching materials must be developed. Oxygen enriching materials that have been examined include cobalt porphyrin, iron phthalocyanine, artificial hemoglobin, membranes and perfluorochemicals (PFCs). PFCs have high oxygen solubility, low surface tension and viscosity to enhance O2 diffusivity and Li+ transference number as well as wettability of the cathode surface, high chemical and thermal stability, hydrophobicity and low flammability. In the Li-O2 battery the PFC must be miscible with the polar organic solvent and resistant to nucleophilic attack by superoxide anion radical or HOO-. Miscibility of PFCs with polar organic solvents is increased if LiPFOS is used instead of LiTFSI. Increasing O2 pressure increases O2 diffusivity as well as solubility. We will examine many PFCs for susceptibility to nucleophilic attack by superoxide anion radical and HOO- using DFT calculations. Ab initio calculations will also be done to improve our understanding of interactions between PFCs and O2. Other oxygen enriching materials include reversible oxygen carriers like perfluoro cryptands and crown ethers which are known to have high oxygen carrying capacities, while acyclic perfluoro ethers do not bind O2. DFT calculations will be used to examine perfluoro cryptands and crown ethers. Hybrid ionic liquid fluoro-organic solvent mixtures are also promising as they combine the stability to anion attack of ionic liquids with the high oxygen transport and safety of nonflammable fluoro-organics. We intend to use Gaussian 09 for quantum chemical calculations. In Gaussian 09 the DFT calculations scale well up to 64 processors, however the high-level ab initio methods scale only up to 16 processors. Therefore these calculations do require a longer execution time. Industry partnership: Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 100000 Q1: 25000 Q2: 25000 Q3: 25000 Q4: 25000 Justification: Storage requirements: Thank You, The LCRC Accounts System

1 0

Re: [allocations-admins] [LCRC Accounts] Project Request: CEES-II-Wolverton
by John Blaas 04 Sep '15

04 Sep '15

Created - JB On Fri, Sep 4, 2015 at 12:22 PM, Bair, Raymond A. <rbair(a)anl.gov> wrote: > This project also looks OK. > > Suggest allocating 100K for FY15 on Blues, and telling them they will also > need to submit a FY16 request. > > Category: Physical Sciences > > Subcategory: Materials Science > > POC: Larry Curtiss > > > > > ----------------------------------------- > Ray Bair > Computing, Environment, and Life Sciences > Argonne National Laboratory > and the University of Chicago > TCS Building 240, Room 4122 > 9700 South Cass Avenue > Argonne, IL 60439 > email: rbair(at)anl.gov > Phone: (630)252-5751 > > > > > > On 9/4/15, 11:42 AM, "allocations-admins-bounces(a)lcrc.anl.gov on behalf of > accounts(a)lcrc.anl.gov" <allocations-admins-bounces(a)lcrc.anl.gov on behalf > of accounts(a)lcrc.anl.gov> wrote: > >>Hello, >> >>A new project on the LCRC cluster has been requested. Please forward >>the information on to the LCRC Allocation sub-committee. >> >> Applicant's name: Chris Wolverton >>Applicant's institution: ANL >> Applicant's division: Computing, Environment, and Life Sciences >> Project Name: CEES-II-Wolverton >> Project title: DFT Computation of Hybrid and Li-ion Battery >>Materials >> Associated funding: CEES-II EFRC >> Other Systems: >> Science: Recent experiments have shown that lithium and >>oxygen can be electrochemically removed from Li5FeO4 (5Li2OÂ·Fe2O3) and >>re-accommodated during discharge, creating the possibility of its use as >>a high-capacity electrode in a hybrid Li-ion/Liâ€“O2 electrochemical >>cell. Taking this novel chemistry as a model, we use density functional >>theory (DFT) within a high-throughput framework to screen for analogous >>reactions in other materials. We also are interested in determining the >>mass tranport kinetics of the phase transformations in these materials. >> Project description: 1. Thermodynamics studies including electronic >>structure calculations, phase transformation calculations for new Li-ion >>and hybrid Li-ion/Li-O2 battery chemistries. >>2. Kinetics studies including defect formation energy calculations, >>ab-initio molecular dynamics, nudged elastic band calculations and >>kinetic Monte Carlo simulations for Li/O transport in hybrid materials >>including Li-Fe-O and Li-Mn-O. >>3. New high-throughput DFT discovery of novel hybrid Metal-ion/Metal-O2 >>battery chemistries, novel battery anode/cathode materials. >>4. Structure predictions of new phases observed in the >>charging/discharging of transition metal oxides. >> >>Computational methods employed will largely be DFT-based, multiprocessor >>jobs. >> Industry partnership: >> Project URL: >> Requested allocation: 500000 >> Q1: 0 >> Q2: 0 >> Q3: 0 >> Q4: 500000 >> Justification: Our group has considerable experience with >>high-throughput DFT computation, and have demonstrated this in the Open >>Quantum Materials Database (OQMD). OQMD is available online at oqmd.org, >>and consists of a database of >300,000 DFT calculations of known and >>hypothetical inorganic materials. >> Storage requirements: >> >> >>The requester has used undetermined amount hours of their initial startup >>project. >> >>In addition to approving an initial amount, please specify a Category >>and Subcategory for this project. For a list of the current selection >>of approved categories, please see: >> >> https://wiki.lcrc.anl.gov/wiki/Processes/Categories >> >>Once the Allocation committee has approved the project, please go to >>the Project Management page to create it: >> >>https://accounts.lcrc.anl.gov/projects.php >> >>Thank You, >>The LCRC Accounts System > > _______________________________________________ > allocations-admins mailing list > allocations-admins(a)lcrc.anl.gov > https://lists.lcrc.anl.gov/mailman/listinfo/allocations-admins

1 0

Re: [allocations-admins] [LCRC Accounts] Project Request: Bubble_superlattice
by John Blaas 04 Sep '15

04 Sep '15

Created. - JB On Fri, Sep 4, 2015 at 12:16 PM, Bair, Raymond A. <rbair(a)anl.gov> wrote: > PPS. 750K is way too much to use before 9/30. > > Please let t hem know that they will need to submit another request for > FY16. > > Lets start them at 100K > > Ray > > > > On 9/4/15, 12:10 PM, "allocations-admins-bounces(a)lcrc.anl.gov on behalf of > Bair, Raymond A." <allocations-admins-bounces(a)lcrc.anl.gov on behalf of > rbair(a)anl.gov> wrote: > >>P.S. >> >>Category: Physical Sciences >> >>Subcategory: Materials Science >> >>POC: Elia Merzari >> >> >> >> >> >>On 9/4/15, 12:03 PM, "allocations-admins-bounces(a)lcrc.anl.gov on behalf of >>Bair, Raymond A." <allocations-admins-bounces(a)lcrc.anl.gov on behalf of >>rbair(a)anl.gov> wrote: >> >>>This looks fine to me, to start on Blues. >>> >>>John low - are you part of this project effort? >>> >>>Ray >>> >>> >>> >>>On 9/4/15, 8:37 AM, "allocations-admins-bounces(a)lcrc.anl.gov on behalf of >>>accounts(a)lcrc.anl.gov" <allocations-admins-bounces(a)lcrc.anl.gov on behalf >>>of accounts(a)lcrc.anl.gov> wrote: >>> >>>>Hello, >>>> >>>>A new project on the LCRC cluster has been requested. Please forward >>>>the information on to the LCRC Allocation sub-committee. >>>> >>>> Applicant's name: Zhigang Mei >>>>Applicant's institution: ANL >>>> Applicant's division: NE >>>> Project Name: Bubble_superlattice >>>> Project title: Atomistic Simulation of Fission Gas Bubble >>>>Superlattice in Irradiated Materials >>>> Associated funding: NNSA >>>> Other Systems: Carbon at CNM >>>> Science: The accumulation of gaseous species in nuclear >>>>fuel leads to deleterious microstructural changes that are of utmost >>>>concern to both fission reactor applications [Trinkaus, J. Nucl. Mater. >>>>323 (2003) 229]. Inert gas elements â€“ such as helium, xenon and >>>>krypton >>>>- are generated due to fission reactions in nuclear fuel. In general, >>>>the >>>>precipitation of gaseous species into gas-filled bubbles leads to >>>>volumetric swelling in fuels. According to conventional nucleation >>>>theory, in the early stages of irradiation, gas atoms diffuse throughout >>>>the crystal and begin to form clusters due to their insolubility in the >>>>solid. This clustering can initiate either by chance encounters of the >>>>wandering gas atoms, or by gas-atom trapping at microstructural >>>>segregation sites such as grain boundaries (GBs) [Rest, J. Nucl. Mater. >>>>207 (1993) 192]. The subsequent growth or shrinkage of a gas bubble is >>>>governed by the fluxes of vacancies, interstitials, and gas atoms to or >>>> away from the bubble surface. If gas bubbles are located on sinks (such >>>>as GBs), they may grow indefinitely to the point of interconnection, >>>>thus >>>>lead to rapid fission gas release to the exterior of fuel. It is found >>>>that the formation of micro-sized fission-gas bubbles at GBs is the >>>>major >>>>reason leading to the fuel swellings at high fission density, while >>>>nano-sized intragranular gas bubbles have negligible contribution to the >>>>overall fuel swelling. Therefore a major task for fuel development is to >>>>control the fission gas bubble microstructures and to retain more >>>>fission-gas bubble inside fuel grains at high fission density. Some of >>>>the proposed approaches include (i) Enhancing the solubility of fission >>>>gas in fuel by modifying the fuel composition and (ii) Increasing the >>>>grain size in the fuel by heat treatment. So far, these approaches have >>>>not been well tested and their effects on the nucleation and growth of >>>>fission gas bubbles are not clear. >>>>Recent experiments by Gan et al show that fission gas bubbles form fcc >>>>superlattice in the irradiated bcc U-7Mo dispersion fuel [Miller et al., >>>>J. Nucl. Mater. 458 (2015) 115]. Typical bubble size and spacing in >>>>these >>>>bubble superlattices are in the range of 2.75-4.5 nm and 10-12 nm, >>>>respectively. Although ordered bubble superlattice has also been seen in >>>>ion-irradiated materials, common observations show that superlattice >>>>will >>>>primarily form in the same structure and crystal orientation as the host >>>>material. Meanwhile the formation of bubble superlattice is >>>>counterintuitive to the fact that fission gas is randomly generated in >>>>lattice and gas bubbles should be nucleated in a random manner >>>>initially. >>>>Our own TEM characterization of Xe irradiated U-Mo however shows that >>>>gas >>>>bubbles were randomly distributed in grain instead of forming ordered >>>>superlattice. >>>>The goal of this proposal is to investigate the potential mechanisms of >>>>the formation and collapse of the Xe bubble superlattice in irradiated >>>>U-Mo alloys using atomistic simulations. We hope this study will provide >>>>a microscopic model of the nucleation and growth of gas bubble inside >>>>fuel grains and therefore better control of gas bubble microstructure >>>>under radiation. >>>> >>>> Project description: We will use molecular dynamics (MD) to >>>>investigate the potential mechanism of the formation of Xe bubbles >>>>superlattice in U-Mo alloys. The obtained simulation results will be >>>>compared to the microstructure characterized by TEM in irradiated U-7Mo >>>>fuels. A ternary U-Mo-Xe potential has been previously developed by >>>>Smirnova based on embedded atom method (EAM) [Smirnova et al. Modelling >>>>Simul. Mater. Sci. Eng. 21 (2013) 035011]. However our test shows that >>>>this potential cannot predict the accurate formation energy of Xe >>>>defects >>>>in U-Mo. Therefore, we will use the so-called force matching method as >>>>implemented in potfit [Brommer, Modelling Simul Mater Sci Eng 15 (2007) >>>>295] to develop a new potential for U-Mo-Xe based modified EAM (MEAM). >>>>To >>>>build a potential suitable for the simulation of a complicated ternary >>>>system, we have to prepare an extensive set of reference configurations >>>>representing all kinds of possible structures. Each configuration is cor >>>> responding to one of the possible states of the U-Mo-Xe system. VASP >>>>will be used to calculate energy, force and stress of the reference >>>>configurations with atoms up to 150. The total computational time using >>>>DFT will be 150000 CPU-hours. >>>>To model different configurations of Xe gas bubbles in U-Mo alloys, a >>>>120Ã—120Ã—120 cell (40nmÃ—40nmÃ—40nm) based on bcc structure will be >>>>constructed. About 3.5 million atoms will be introduced in the >>>>simulation >>>>box, which allows adding up to 110 gas bubbles with size around 2.5 nm. >>>>We will compare the energetics of different bubble superlattices, such >>>>as >>>>cubic, fcc, bcc, hcp and disordered bubbles configurations. We will also >>>>investigate the effect of Mo concentration on the retention of Xe atoms >>>>in the lattice. Two different alloys, i.e., U-7wt%Mo and U-10wt%Mo, will >>>>be studied and be compared to pure bcc Mo and U cases. Meanwhile, >>>>temperature plays an important role in governing the fluxes of >>>>vacancies, >>>>interstitials and gas atoms to or away from the bubble surface. The >>>>interested temperature range is between 300 K and 1000 K. In experiment, >>>>it was observed that the gas bubble superlattice collapses at high >>>>fission density. A major effect of fission on the microstructure >>>> is creating a large amount of Frenkel pair defects in the lattice. >>>>Vacancy can provide efficient diffusion channels for Xe atoms. In this >>>>work, we will investigate the effect of five parameters (Xe >>>>concentration, Xe bubble configuration, Mo concentration, temperature, >>>>and Frenkel pair concentration) on the stability of gas bubble >>>>superlattices introduced in U-xMo alloys. By systematic analysis of the >>>>bubble superlatticeâ€™s microstructure and their energetics, we will be >>>>able to correlate the key parameters to the formation of bubble >>>>superlattice, and provide a potential mechanism of its formation in >>>>U-Mo. >>>>Combining all the parameters, we will expect about 50 production jobs. >>>>Our initial test shows that a single MD simulation for 1 nano-second >>>>takes more than 12000 CPU-hours (256 CPUÃ—24 hours). We therefore >>>>request >>>>the total computational time of 750000 CPU-hours. >>>> >>>> Industry partnership: >>>> Project URL: >>>> Requested allocation: 750000 >>>> Q1: 0 >>>> Q2: 0 >>>> Q3: 0 >>>> Q4: 750000 >>>> Justification: The main calculations are performed by high >>>>efficient molecular dynamics code LAMMPS. The parallel efficiency test >>>>for this code shows that it can be well scaled to up to tens of >>>>thousands >>>>of CPUs. Other DFT calculations will be performed by VASP, which is one >>>>of the widely used DFT code. >>>> Storage requirements: 1 TB >>>> >>>> >>>>The requester has used undetermined amount hours of their initial >>>>startup >>>>project. >>>> >>>>In addition to approving an initial amount, please specify a Category >>>>and Subcategory for this project. For a list of the current selection >>>>of approved categories, please see: >>>> >>>> https://wiki.lcrc.anl.gov/wiki/Processes/Categories >>>> >>>>Once the Allocation committee has approved the project, please go to >>>>the Project Management page to create it: >>>> >>>>https://accounts.lcrc.anl.gov/projects.php >>>> >>>>Thank You, >>>>The LCRC Accounts System >>> >>>_______________________________________________ >>>allocations-admins mailing list >>>allocations-admins(a)lcrc.anl.gov >>>https://lists.lcrc.anl.gov/mailman/listinfo/allocations-admins >> >>_______________________________________________ >>allocations-admins mailing list >>allocations-admins(a)lcrc.anl.gov >>https://lists.lcrc.anl.gov/mailman/listinfo/allocations-admins > > _______________________________________________ > allocations-admins mailing list > allocations-admins(a)lcrc.anl.gov > https://lists.lcrc.anl.gov/mailman/listinfo/allocations-admins

1 0

New LCRC report submitted for protein_e-wire
by support＠lcrc.anl.gov 04 Sep '15

04 Sep '15

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2015/?project=protein_e-wire

1 0