March 2011 - Allocations-admins - mailman3.cels.anl.gov

[LCRC Accounts] Project Allocation Request
by accounts＠lcrc.anl.gov 24 Mar '11

24 Mar '11

Hello, A change in allocation has been requested: Requester: zapol (Peter Zapol) Project: nanocatalysis Title: Catalysis in nanostructured materials Description: Molecular dynamics studies using many-body potentials as implemented in DL_POLY computer code and DFT studies in VASP will be used to simulate support structures covered by hydroxyl groups. Radial distribution functions will be compared to available experiments. The code uses 32 to 48 PEs for about 50,000 atom calculations. The geometries from molecular dynamics simulations will be used in studies of catalytic activity. We will study reactions on supported metal subnanometer clusters. We will also continue investigations on using thermodynamics to modify shape of catalytic particles, in particular in electroche4mical environment. Density functional studies will be performed using VASP, NWChem and GAUSSIAN codes to determine reaction energies and barriers. The VASP calculations typically use 24-64 processors for 24 hours to 48 hours. Expected number of members in the project is three to six. Current: undetermined amount Justification: We have used our allocation very effectively in the previous year. Requested: 400000 A specific reason has been given: We have been successful in utilizing allocation and need to continue our computations This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System

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[LCRC Accounts] Project Allocation Request
by accounts＠lcrc.anl.gov 24 Mar '11

24 Mar '11

Hello, A change in allocation has been requested: Requester: zapol (Peter Zapol) Project: nanocatalysis Title: Catalysis in nanostructured materials Description: Molecular dynamics studies using many-body potentials as implemented in DL_POLY computer code and DFT studies in VASP will be used to simulate support structures covered by hydroxyl groups. Radial distribution functions will be compared to available experiments. The code uses 32 to 48 PEs for about 50,000 atom calculations. The geometries from molecular dynamics simulations will be used in studies of catalytic activity. We will study reactions on supported metal subnanometer clusters. We will also continue investigations on using thermodynamics to modify shape of catalytic particles, in particular in electroche4mical environment. Density functional studies will be performed using VASP, NWChem and GAUSSIAN codes to determine reaction energies and barriers. The VASP calculations typically use 24-64 processors for 24 hours to 48 hours. Expected number of members in the project is three to six. Current: undetermined amount Justification: We have used our allocation very effectively in the previous year. Requested: 400000 A specific reason has been given: We have been successful in utilizing allocation and need to continue our computations This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System

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[LCRC Accounts] Project Allocation Request
by accounts＠lcrc.anl.gov 24 Mar '11

24 Mar '11

Hello, A change in allocation has been requested: Requester: zapol (Peter Zapol) Project: compnano Title: Computational Nanoscience Description: Computational studies aimed at materials by design will be performed using molecular orbital theory, density functional and molecular dynamics methods as implemented in Gaussian09, VASP, and NWChem computer codes. We have successfully performed NWChem, G09 and VASP calculations on Fusion last year. G09 scales well up to 16 processors. VASP shows good scalability from 16 to 256 PEs as well as NWChem which is highly suitable for massively parallel computations. We will also investigate how other codes scale on Fusion and benchmark performance. We will continue our studies of chemical reactivity on the surfaces and interfaces of nanomaterials in FY11. In particular, we will perform DFT calculations coupled to thermodynatic treatments to investigate properties of nanoparticles as a function of their size and shape for metals and metal oxides. We have performed work on computational screening of oxide-based materials for light to energy conversion that resulted in useful predictions for surface modification. We plan to extend these studies to doping with light elements for oxide band gap engineering and transition metals for modifications of catalytic properties. We will extend these studies to different size and shape of oxide particles. In addition, we will work on carbon nanomaterials using them both as support for heterophase nanostructures with novel chemical properties to investigate their potential for electrochemical applications in energy conversion and storage. A typical Gaussian calculation will take for 4 to 16 nodes anywhere from 1-2 hours to several days. VASP and NWChem calculations may involve 16 to 256 nodes and up to several days depending upon the size of the problem. This project will involve 5-7 members of the Molecular Materials Group. Current: undetermined amount Justification: The allocation is used by several postdoctoral and staff scientists to perform calculations on DOE-funded projects. From previous year's experience, we have used efficiently a large allocation, about a third of time for Gaussian and NWChem, and the rest for VASP calculations. Requested: 400000 A specific reason has been given: We have added more postdocs and utilization is higher This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System

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[LCRC Accounts] Project Allocation Request
by accounts＠lcrc.anl.gov 22 Mar '11

22 Mar '11

Hello, A change in allocation has been requested: Requester: jlow (John J. Low) Project: aimd_catalysis Title: Ab Initio Molecular Dynamics for Catalysis of Biomass to Fuels Description: We will use CPMD to model reactions in aqueous phases. This program has the very efficient Carr-Parinello algorithm for AIMD and several different methods for thermodynamics sampling including metadynamics, umbrella sampling and the Blue-Moon ensemble. CPMD is an excellent tool for modeling reactions in liquids and sampling phase space. The parallel performance of CPMD is fair. The unit cell for our model of glucose in sulfuric acid contains 230 atoms and a unit cell volume of 2500 Å3. The MPI version of CPMD had a parallel efficiency of 70% on 160 processors for this model. The number of planes in the real space grid limits the number of processors which can be used efficiently by CPMD. We plan to implement a hybrid (MPI/OPENMP) version of CPMD of version which should increase the parallel efficiency of CPMD significantly by allowing multiple processors (up to eight on Fusion) to work on each plane of the real space grid and reducing the overhead from MPI All_to_All communication. A metadynamics run of 10ps is adequate to model a step in the glucose decomposition reaction. Ten picoseconds require 7.3 kilocore-hours. We plan to model 20 reaction pathways in the glucose to HMF reaction mechanism. This work will require approximately 150 kilocore-hours. Simulation time of 10ps will be required to sample the phase space of bimetallic metal clusters. We estimate that each of trajectories will require a kilocore-hour. We plan to model the geometry of ten different metal alloy clusters. We will also simulate these clusters with chemisorbed hydrogen and oxygen. This work will require 50 metadynamics runs or 50 kilocore-hours. Current: undetermined amount Justification: Requested: 100000 A specific reason has been given: Additional calculations are required to benchmark AIMD calculation with respect to the G4 calculations of Rajeev and Curtiss This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System

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[LCRC Accounts] Project Request: Linr_sclng_catalysis
by accounts＠lcrc.anl.gov 22 Mar '11

22 Mar '11

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: John J. Low Applicant's institution: ANL Applicant's division: MCS Project Name: Linr_sclng_catalysis Project title: Linear Scaling Electronic Structure for Catalysis in nanobowls. Associated funding: of Energy, Office of Science, and Office of Basic Energy Sciences Other Systems: None Science: Metal clusters supported in metal oxide nanobowls are being synthesized by the Institute for Atom-efficient Chemical Transformations (IACT). These nanobowls are synthesized by depositing several layers of an oxide (i.e. Al2O3) with atomic layer deposition [i.e. Al(CH3)3] on another a substrate oxide (i.e. SrTiO3). Complexes (i.e. Fe-calixarene) on the substrate oxide form nanobowls in the deposited oxide. These nanobowls have diameters of about 1-2 nm. Modeling the chemistry in 1 nm nanobowls will require cells with a volume of 10 cubic nanometers containing thousands of atoms. The computational effort for VASP, GPAW and other plane wave code scales like the number of electrons to the third power. Although simulations of this magnitude are possible with VASP or GPAW on high performance supercomputers, programs like CP2K implement linear scaling methods of electronic structure require an order of magnitude less computer time than conventional electronic structure codes for models containing a thousand atoms. CP2K will allow the efficient modeling of the catalytic chemistry in nanobowls at the atomic level. Project description: The linear scaling program CP2K can handle models containing 1000s of atoms efficiently. CP2K has been shown to scale well to 256 processors for a model containing 1028 water molecules. The elapsed time required for a calculation containing a thousand atoms is approximately 28 hours on 256 processors (7,000 hours) to optimize the geometry for a metal cluster in a nanobowl. We plan to run geometry optimizations for models of nanobowls, metal clusters in nanobowls and chemisorption of H, O and CHx species on metal clusters in nanobowls. Performing these calculations on three different combinations of metal oxides will demonstrate whether metal-support interactions alters the chemistry of a metal cluster in a nanobowl and the utility of this approach to modeling chemistry in nanobowls. The twenty-four calculations described here will require 200,000 hours of CPU. Project URL: Requested allocation: 200000 Justification: The requester has used 0 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

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[LCRC Accounts] Project Allocation Request
by accounts＠lcrc.anl.gov 22 Mar '11

22 Mar '11

Hello, A change in allocation has been requested: Requester: wiringa (Robert Wiringa) Project: qmc_for_nuclei Title: Quantum Monte Carlo Calculations of Light Nuclei Description: In FY10 we did not make as much use of Fusion as expected - about 70,000 CPU hours total (counting early FY10 hours on Jazz as half-hours on Fusion), partly because we made extensive use of the MCS SiCortex and ALCF Blue Gene for major parts of our research. We expect to continue using those other resources but the SiCortex time is not guaranteed, and it seems that the machine is getting shaky. In FY11 there will be three staff members and three postdocs working on the project. We would like to do the following: A) GFMC Nucleon-Nucleus Scattering We are continuing our studies of nucleon-nucleus scattering for n+3H, p+3He, n+4He, and p+4He, and for parity-violating (PV) n+4He scattering. Eventually we will continue to larger systems, but there are still some unresolved issues with the 3+1 and 4+1 scattering cases. Based on current experience with Fusion, we will need about 30,000 CPU hours to complete the present studies. B) Transitions in A=8-10 Nuclei We have been studying electromagnetic transitions in 10Be and 10C in collaboration with the PHY low-energy experimental group, funded by a joint LDRD project. These studies show a surprising sensitivity to details of the nuclear Hamiltonian, in particular the three-body forces, which we need to explore further. A new postdoc is arriving this fall who will be studying meson-exchange-current contributions to magnetic moments and transitions in A=8-10 nuclei. We are also starting to provide transition densities in 9Be and 10B to help explain pion inelastic-scattering and new neutrino scattering data. For this work we expect to use 50,000 CPU hours in FY11. C) Unnatural-parity and double-intruder states We have been making GFMC calculations for the unnatural-parity excitations (where one nucleon is excited to the next nuclear shell) in 9Be and VMC calculations for unnatural-parity states in 10Be and 10B. We wish to continue this work in FY11, including double-intruder states in A=10 that have two nucleons excited to the next shell, and the parity-inversion in 11Be, where the 1/2+ intruder state is the ground state. Again, we wish to explore the sensitivity to different nuclear Hamiltonians, and estimate the need for 50,000 CPU hours in FY11. D) Neutron drops We will continue to use Auxiliary Field Diffusion Monte Carlo (AFDMC) and GFMC to compute properties of large systems of neutrons. These will be both neutron drops and neutron matter done in periodic boundary conditions. We have two tasks: 1) to provide guidance to the development of energy density functional theories as part of the UNEDF SciDAC, and 2) to test the effect of three-body forces, fitted to light nuclei, in neutron matter. Based on our work this past year, we estimate 30,000 hours for this work in FY11. The Quantum Monte Carlo methods work very efficiently on parallel processors. We use MPI and see speed-up efficiencies better than 95% for up to 250 CPU's on Fusion, with sustained speeds of 1.8 GFLOPS/CPU. Using ADLB and OpenMP on BG/P we have run efficiently on 130,000 processors. We have already demonstrated that OpenMP also works well for us on Fusion for larger nuclei. This all adds up to 160,000 hours. Current: undetermined amount Justification: Requested: 80000 A specific reason has been given: Our original request for FY2011 was 160,000 hours, and we haved used almost 80,000 hours in the first six months. We are proceeding according to plan and would like a full 80,000 hours in the second half of FY2011. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System

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[LCRC Accounts] Project Request: biomimetic_systems
by accounts＠lcrc.anl.gov 21 Mar '11

21 Mar '11

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: Oleksandr Kokhan Applicant's institution: ANL Applicant's division: CSE Project Name: biomimetic_systems Project title: Solar energy conversion in biomimetic molecular architectures Associated funding: DOE Division of Chemical Sciences, Geosciences, and Biosciences Other Systems: N/A Science: This computational project will supplement our experimental work on construction and characterization of biomimetic molecular architectures for solar energy conversion. The first aim is to use Molecular Dynamics (MD) simulations to estimate changes in the hydration layer and structural flexibility of PpcA, a multiheme c-type cytochrome from Geobacter sulfurreducens, induced by binding of various photosensitizers. These results will facilitate interpretation of Wide Angle X-ray Scattering (WAXS) data. The second aim is to explore a possibility of using other members of the Ppc family and similar closely related multiheme cytochromes, as well as their genetically modified forms as hosts for photosensitizers. Project description: We are developing biomimetic molecular architectures for efficient solar energy conversion using artificial and natural photosensitizers combined with natural and genetically engineered host systems capable to support long-lived charge-separated states and conduct charges away from the photosensitizers. Our experimental data suggests that PpcA, a multiheme redox protein from Geobacter sulfurreducens, forms light-activated electron transfer complexes with a series of light-harvesting chlorophyll analogues, such as protoporhyrin IX, chlorin e6 and tetrakis(4-sulfonatophenyl)porphine. However, currently there are no X-ray crystal or NMR structures of photosensitizer-cytochrome complexes available. We intend to run a series of all-atom 0.1-0.5 μs MD simulation with and without exogenous ligands in order to validate and refine tentative photosensitizer binding sites predicted with Dock 6.4 This will also allow us to generate a set of experimentally testable hypothesis for the predicted binding sites. The proposed simulations will be performed with explicit solvent and periodic boundary conditions, constant pressure and temperature using CHARMM force field and NAMD 2.7. Force field parameters for photosensitizers will be developed using Gaussian09. Initial atom coordinates for hosts will be from the structural data available from the PDB Databank or from the Schiffer group (BIO, ANL). The analysis of MD trajectories, computational docking and calculation of X-ray scattering profiles will be carried out on our lab computers. NAMD is a highly scalable molecular dynamics simulations code. Benchmarks on Fusion with PpcA in a water box (~13,000 atoms total) showed more than 99% speed-up efficiency with ~1,600 atoms/CPU core and ~80% efficiency with ~400 atoms/core and yielded 5.1 and 15.7 ns/day, respectively. Project URL: http://www.cse.anl.gov/fundamental_interactions/solar_conversion.html Requested allocation: 400000 Justification: The requester has used 5474 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

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[LCRC Accounts] Project Allocation Request
by accounts＠lcrc.anl.gov 21 Mar '11

21 Mar '11

Hello, A change in allocation has been requested: Requester: handany (Handan Yildirim) Project: md_pls_dft_for_TiO2 Title: First Principles and Classical Molecular Dynamics Calculations of Lithium Intercalation into TiO2 Surfaces and Nanostructures Description: The problem is inherently multi-scale in nature, and the ultimate answer to those observed features could only be provided using a multi-scale simulation approach. Thus, we will treat the problem using both DFT and MD simulations. At the first stage of the calculations we will use MD simulations (at low and high temperature – ranging form 300K to 700K) for a long enough time (~ 5ns at the current studies) to observe/learn about the details of the Li diffusion processes in both crystalline and amorphous TiO2 bulk structures at lithium concentrations relevant for battery electrode operation (ranging from 25% to 100% interstitial lithium). Using these observed processes as an input, we will calculate the corresponding energetics, diffusion pathways and dynamics using periodic Density Functional Theory calculations. MD results will also be expected to provide possible differences in the diffusion and dynamics of Li in crystalline and amorphous structures. On the other hand, using DFT, we will explore detailed electronic structures of the crystalline and amorphous TiO2 to understand and validate the observations obtained from MD simulations for both systems. The second phase of these analyses will be devoted to reveal the effect of nano-structuring and morphology on the above-mentioned properties. For this part of the work, we will explore Li diffusion energetics and dynamics in crystalline and amorphous nanotubes and nanoparticles of TiO2 by changing the size, length and diameter (in the case of tube) of these nanostructures. For this stage, we will vastly benefit from the ability of classical MD simulations that allow simulation of several thousands of atoms. We will explore the size effects on Li intercalation properties. The third stage of the calculations will be devoted to investigating electric field effects on the Li diffusion energetics and dynamics on both crystalline and amorphous TiO2. We will apply an electric field less than the break down potential of TiO2 on both crystalline and amorphous structures, and explore the field effects with low and high Li concentrations. Our goal in this part of the study is to separate the effect of field from that of the concentration and thus to evaluate the role of each parameter in Li diffusion. These calculations are expected to provide further insights into the role of field on both crystalline and amorphous structures thus help to explain the observed amorphous to crystalline phase transition. These calculations will be performed using MD simulations at both low and high temperatures, and for ns range simulation times. In preliminary work, we have obtained several results for the diffusion and absorption of Li in TiO2 Anatase bulk both using DFT and MD simulations. Using DFT (the VASP code), we have calculated three absorption energies and diffusion activation barriers for three diffusion processes of Li. We have analyzed the results of MD simulation at both 500K and 700K to identify the possible Li diffusion processes, and used these processes to calculate the corresponding energetics using DFT. Our preliminary DFT results show that Li prefers to sit at the octahedral site at which it is six- coordinated. The diffusion mechanism of Li is observed to facilitate through hopping from an octahedral to octahedral site that leads to the lowest activation energy barrier as compared to those other two processes. We also note that the existence of Li leads a shift in Fermi level as noted in the literature. Lets us note that the presence of oxygen makes our DFT calculations quite expensive since we need to use large enough energy cut off (500eV is used at the current simulations). For sufficient convergence of the total energy of about 100 atoms system with the chosen parameters requires 100 plus ionic iterations. For the recent simulations, we have mostly used 32 CPU’s per job, and at least 5 jobs, on average, run simultaneously; we expect a similar distribution of jobs when running VASP on Fusion. Depending on the requirement for finer converged energies, we will be adjusting these parameters. Note that we will also be exploring Li adsorption and diffusion on other such systems as Anatase and Rutile surfaces, nanoparticles of several sizes, nanotubes, and amorphous TiO2 thus it is inevitable that we require significant computational resources to complete this part of the proposed study. We have also performed preliminary classical MD simulations to study Li diffusion energetics and dynamics under several conditions using the DL-POLY code. Our preliminary results for Li diffusion in Anatase TiO2 bulk provided several insights for Li behavior in such system. Upon relaxation, we find that Li prefers to sit at the octahedral site as observed in our DFT study. We have performed several MD simulations for single Li diffusion at temperatures ranging from 300K to 700K for simulation times ranging from 500ps to 5ns. We find that it is not possible to observe diffusion at low temperature as 300K due to high correlation time of ~1 microsecond reported. However, the diffusion at higher temperatures (500K and above) is observed, and found to facilitate through hopping between octahedral sites. We have also managed to obtain an amorphous TiO2 starting from Anatase bulk, and the obtained amorphous phase is in very good agreement with that of reported in an experimental stu dy. We are currently exploring several such aspects of Li diffusion (in both crystalline and amorphous structures) as concentration, temperature, and field effects to understand the role of each individual parameter in the experimentally observed phase transition. Note that these simulations have to be performed with a very fine timestep (~0.2 fs in general), thus requires long simulation hours even for 5ns. For the current calculations we have systems of nearly 3000 to 5000 atoms. For 5ns simulation, we need 25 millions simulation step, and note that we are exploring the diffusion events at both low and high temperatures. Lets us note that, for system size of 3000-5000 atoms using 0.2fs time step, the simulation of 5ns at low temperatures with Li loaded in the system requires approximately 10 days using 32 CPU’s. We anticipate that we will be running of about 5 to 10 jobs per day to complete this part of the proposed research. Our simulations also indicate that for the ca lculations with field introduced, the required time step is even finer. Our calculations will be extended to study the same phenomenon for the above-mentioned nanostructruced systems thus we will be in need of significant computational resources for the completion of this proposed study. Current: undetermined amount Justification: In roughly three and a half months, we required over 250,000 CPU hours for the combination of MD and DFT calculations that also include testing of classical potential used, and the convergence tests for DFT studies. These calculations have been performed on the CNM’s carbon cluster, but this resource is fully subscribed and is being increasingly used for external user projects. Thus, we require substantial computational resources on Fusion to complete our proposed project. For a full year, we estimate that approximately 550,000 CPU hours will be sufficient. Requested: 300000 A specific reason has been given: I have used about 200000 core-hours approximately for the last six months. I would like to request allocation time to increased to 300000 core-hours. The project involves both DFT and extensive MD simulations that require substantial time. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System

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[LCRC Accounts] Project Allocation Request
by accounts＠lcrc.anl.gov 21 Mar '11

21 Mar '11

Hello, A change in allocation has been requested: Requester: rrankin (Rees Rankin) Project: DFT_TM_Catal_Screen Title: DFT Screening Investigation on Catalytic and Electrocatalytic Phenomena of Transition Metals Description: In the previous work in FY2009 and 2010 we performed DFT calculations to begin to study an important reaction in the context of fundamental heterogeneous catalytic as well as electrocatalytic applications, as well as build our computational database and Sabatier Volcano analytical methods. Specifically, this reaction involved the selective reduction of molecular oxygen (O2) by TM catalysts to hydrogen peroxide (H2O2). The applications of studying this reaction were numerous. It is well known that H2O2 historically has not been synthesized efficiently via direct conversion of H2 and O2. Recent work in the literature suggests metallic alloy nanoparticles can create new chemistry in the selective synthesis of H2O2 from H2 and O2. After completing our initial work (flat, and stepped surfaces of 'pure' single component TM species) on this reaction in FY2009/FY2010, we have begun initial work towards similar studies using the same methods to characterize selecti ve product reactions in the electrochemical reduction of CO2 (CDR) towards more economically and environmentally beneficial target species. Compared to the previous work on H2O2 this is a much more complex reaction network to study (with more paths and branchpoints) that requires significantly more calculations of potential descriptors and transition states to determine the appropriate Sabatier Volcano relations. However, by building on the knowledge generated from such studying such critical, and fundamental reactions, it will be much more feasible to predict the performance of novel catalysts in other reactions which involve the same or similar reactants and intermediates but different products, or conversely, differing reactants with similar intermediates and products. Our work will continue to supplement the computational materials-by-design and Materials Design Workbench database being developed. The results of populating the MDW database will allow far greater amou nts of materials and catalyst reactions to be quickly predictively screened in the future. Calculations will be expected to be performed using the Vienna ab initio Simulation Program (VASP). This program , currently deployed on Fusion, uses a periodic plane-wave representation of the electronic wavefunctions of materials with a self-consistent minimization/solution under the Density Functional Theory (DFT) formalism. Recent improvements in the parallelization of VASP combined with the excellent parallel hardware capabilities in the LCRC Fusion system allow for reasonably efficient near-linear scaling for jobs running on up to ~ 80 cores (10 nodes). Superlinear scaling can occasionally now even be seemingly witnessed for small jobs in a single compute node with appropriate cache sizes. Additional calculations in the future may utilize the Dacapo DFT code, which performs similarly to VASP in the above regards Ongoing and previous calculations for this work have already been performed on the HPC Carbon cluster available at the CNM (ANL), and the Fusion system at LCRC (ANL) in FY2009/FY2010, and are continuing into FY2011. However, the resources available at CNM-ANL Carbon cluster are currently significantly overloaded even after the recent hardware expansion; small scale jobs can actually sit in the submission queue for time intervals longer than their execution related wall time. An allocation of 750k core hours on LCRC-Fusion would ostensibly allow for approximately 1800 calculation-sets (1 calculation-set here can be envisioned as scanning several related materials (such as differently structured surface alloys of the same stoichiometry) + adsorbate over many adsorption sites, or scanning a single material surface +adsorption site over many adsorbates, or as a series of coupled calculations to determine the transition state/activation energy between two local minima). The abil ity to augment our knowledge base with the incorporation of this many additional calculation-sets would be paramount in developing the detailed understanding necessary to move forward in a purely computational catalysis by design (or broader materials by design) project. As a note, we used essentially all of our FY2010 Allocation of 650k hours effectively in ~8-9 months, and we propose to do effectively the same the number of total calculations in FY2011 now that we have a detailed initial understanding of our methods and some basic insights into fundamental reaction mechanisms/TM species we wish to study in vastly greater detail. The availability of high performing computing resources such as Fusion will greatly augment our calculation possibilities and accelerate understanding of our Sabatier relations for the CDR reaction and simultaneously help us continue populating our computational catalysis database. Current: undetermined amount Justification: As a brief summary of typical results, Vasp 4.6 or Vasp 5.x+ with appropriate compilation, Infiniband, and modern processor cores scales well (near linear) out to approximately 80 cores or 10 (Fusion) nodes for most typical calculations on these similar HPC systems. VASP scaling does fall significantly in the regime of calculations with severely large file I/O overhead--however, this is not expected to apply to the jobs performed in the proposed work. We can provide sample benchmarks representative of the type of scaling efficiency our typical calculations have achieved to date on Fusion nodes if necessary. Requested: 250000 A specific reason has been given: Extension of use of prior amount during FY2011 to date. Current research on screening of catalysts for O2 reduction and other related catalytic electrochemistry projects such as CO2 reduction and Lithium Air catalyst chemistry. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System

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[LCRC Accounts] Project Allocation Request
by accounts＠lcrc.anl.gov 21 Mar '11

21 Mar '11

Hello, A change in allocation has been requested: Requester: rmeyer (Randall Meyer) Project: intermetallic Title: Fundamental studies of disparate metals in p/d alloys Description: project has moved in two directions simultaneously over the last year. First, we have finally completed a study of water gas shift catalysis over PdZn(111) and NiZn(111). NiZn and PdZn were chosen for examination as candidates for replacement of copper for low temperature water gas shift as their density of states profiles mirror that of copper. At least three distinct catalytic mechanisms are possible: 1) a redox mechanism whereby CO reacts with O on the surface or 2) a mechanism by which formate (HCOO) produced from CO and OH decomposes or 3) a mechanism which involves a carboxyl (OCOH) intermediate formed from hydroxyl and CO. Rodriguez and Liu had previously found that while the reaction went through carboxyl on Au, the reaction was a redox reaction on Cu. In both cases, the formation of formate was thermodynamically favorable, but formate is far too stable dehydrogenate to release CO2. The redox and carboxyl mechanisms can be compared Redox CO + * ↔ CO* H2O + * ↔ H2O* H2O* + * ↔ OH* + H* OH* ↔ O* + H* OH* + OH* ↔ H2O* + O* CO* + O* ↔ CO2* + * CO2* ↔ CO2 + * H* + H* ↔ H2 + 2* Carboxyl CO + * ↔ CO* H2O + * ↔ H2O* H2O* + * ↔ OH* + H* OH* + CO* ↔ COOH* COOH* + OH* ↔ H2O* + CO2* COOH* ↔ CO2* + H* CO2* ↔ CO2 + * H* + H* ↔ H2 + 2* The first three steps and last two steps are the same in both mechanisms. Previously we have shown that a competition exists between CO oxidation and water activation as the rate limiting step regardless of the mechanism11. On both surfaces, the carboxyl mechanism is preferred over the redox mechanism. However, the rate limiting step in the carboxyl mechanism varies between the two surfaces. Over NiZn(111), the rate limiting step is the reaction between CO and OH to form carboxyl (COOH) whereas over PdZn(111) the dissociation of COOH to CO2 and H has the highest barrier. In both cases, the highest barrier was about 1.00 eV so the overall rate of the reaction may be similar. Over Cu(111), Mavrikakis and co-workers has determined that H2O dissociation is the slow step with a barrier of 1.15 eV12 whereas the barriers for water dissociation over PdZn(111) and NiZn(111) are 0.95 and 0.82 eV respectively. It is interesting to note that the reaction enthalpy over Cu(111) is 0.37 eV whereas it reduces to 0.20 eV over PdZn(111) and is actually exothermic over NiZn(111) (ΔE=−0.26 eV). This work will be submitted for publication in the coming weeks. Second we have performed PDOS calculations on Pt clusters in an effort to understand how the PDOS of Pt is related to the XANES spectra. We have examined both size effects as well as the effect of simple adsorbates such as CO and H2. Our calculations indicate Recent work from Schweitzer et al. suggests that the position of the edge is directly related to the density of states at the Fermi level (and not due to the charge transfer effects). For CO, the d-electron density is significantly depleted and the center of the d-band is shifted away from the Fermi level from −2.61 eV for Pt(111) to −4.17 eV for CO/Pt(111). We hypothesize that the shift in the edge is related to the depletion of states at the Fermi level and that the increase in edge intensity is related to the presence of empty (presumably anti-bonding) states above the Fermi level that are created from hybridization of d-states of the metal with adsorbate states as proposed by Hoffmann. Conversely, in the case of OH, antibonding states are partially filled leading to an increase in electron density near the edge and a shift to lower energy in the simulated XANES. In addition to adsorbate effects, we have also probed size effects. Experimentally we observe a decrease in intensity at the edge as the particle size falls below 3 nm but an increase in intensity slightly beyond the edge. In our preliminary investigation, we have found that simulations of the XANES for a Pt6 cluster as a model of an extremely small cluster, reasonable agreement exists with experiment. However, two competing effects emerge. First, as the particle size shrinks, the average metal-metal coordination number shrinks. This leads to a localization of the DOS and increases the DOS near the edge. However, metal particles are also known to undergo lattice contraction as the particle size shrinks to the nanometer scale. The lattice contraction has been linked to changes in the hybridization of metal bonds as the particle seeks to minimize its undercoordination. Compressing the Pt lattice, moves the d-band center away from the Fermi edge and results in an increase in sta tes 2 eV above the edge as the d-band is smeared over a larger energy range. In our simulations, we find that the loss of intensity at the edge is related to undercoordination while the increase in intensity beyond the edge is related to the diffuse states above the edge arising from lattice contraction. Calculations will continue on two fronts. First, we will move our studies of intermetallics to acrolein hydrogenation. . In this case, four possible intermediates have been suggested which give rise to the two products. Hydroxyallyl and allyloxy could be formed if the aldehyde functionality is hydrogenated as intermediates to the unsaturated alcohol. However, if the double bond is hydrogenated, either 1-formylethyl or 2-formylethyl will serve as an intermediate for hydrogenation to the saturated aldehyde. Density functional theory (DFT) calculations from Rosch and co-workers suggest that over silver surfaces, 1-formyl ethyl is the favored intermediate to the dominant (but undesired) product. We will compare our results over Pd alloys with Pd and Ag monometallic surfaces. Second, we will continue our examination of XANES of supported clusters, focusing on PtMo alloys for which interesting results of WGS exist. Current: undetermined amount Justification: Requested: 200000 A specific reason has been given: I had been given 120,000 hours for the past six months. We have used this time plus a bit more during that allocation period. Therefore, I would like to request an additional 80,000 on top of the 120,000 that I hope to receive for the second half of 2011. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System

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