Basic Energy Sciences Advisory Committee Meeting Omni Shoreham Hotel Washington, DC June 6, 2005 Harriet Kung Division of Materials Sciences and Engineering Office of Basic Energy Sciences, Office of Science U.S. Department of Energy Division of Materials Sciences and Engineering Reflection on BESAC Report on Theory and Computation Basic Energy Sciences Serving the Present, Shaping the Future

Dramatic Progress in Theory and Modeling DFT, ab initio MD, Quantum MC, DMFT, etc. New Computational Capabilities Workstation and Cluster- Universities and Labs Massively Parallel Computers- LBNL/NERSC, PNNL/EMSL, ANL, ORNL Theory and Computation A Confluence of Opportunities in Materials Sciences and Engineering 0.78 Angstroms Direct image of a silicon crystal showing atom columns in pairs only 0.78 Angstroms apart A first-principles method describing the dynamics of magnetic moments in materials Charge Transport in Carbon Nanotubes Source: A.P. Alivisatos New Scientific Frontiers Ultrasmall and Ultrafast Sciences, Quantum-Level Control of Matter and Information, Infusion of Bio Approaches and Techniques Source: A.P. Alivisatos New Experimental Capabilities Tabletop Tools: STM, NMR, STEM, fs-Laser Large Facilities: SNS, NSRCs, LCLS Source: G.M. Stocks et al. Source: S. Pennycook et al.

Theory and Computation in Materials Sciences and Engineering Electronic Structure  Band structure, simulations, model development, many body theory, spin dynamics  Correlation of electronic structure with materials properties; self-organized electronic structure (FQHE, stripes); superconductivity, magnetism, chemical reactivity, hardness, toughness  Dynamics & fluctuations New Materials  New combinations of atoms and new degrees of complexity, e.g., competing interactions among spin, charge, lattice, Vortex matter, Photonic Band Gap Materials, Granular Materials  Nano and other low-dimensional structures  Materials created by energetic processes  Self assembly, pattern formation  Modeling complex fluids, colloids, polymers, and biomolecular materials Surfaces and Interfaces  Electronic surface structure, surface reconstruction  Patterns of crystal growth  Solid – liquid interfaces, corrosive, adhesive, and electrochemical properties  Defects in solids Development of Computational Techniques  Spin Dynamics, Inverse Band Structure, Linear Expansion in Geometric Objects, Algorithm Development, Hyperdynamics

Nanoscale Science Biomimetic Materials and Energy Processes Correlated Electrons in Solids Excited Electronic States Magnetic Spin Systems & Single Electron Devices Defects in Solids Control of Energy, Matter & Information at the Quantum Level Ultrafast Physics and Chemistry Control of Chemical Transformations New Opportunities Identified by the Report Match DMS&E Priorities

Simulations of Self Assembly of Gold Nanoparticles ► Simulations have explored formation of nanocrystals composed of passivated gold clusters. ► Assembly begins by formation of chain structures. The length of the chains formed as well as the nanoparticle size and temperature all affect the resulting properties such as tetragonality, elastic properties of the lattice. ► Another related project has been examining how nanoparticles can be tailored to encourage chosen structures. (i.e., polymer tethers, reactive regions, etc.) New insights on self assembly of nanoparticles were provided by atomistic simulations. DMS&E Theoretical Condensed Matter Physics CRA

Atomistic simulations are being used to gain insight on the unit processes involved in deformation. This array of pyramids was revealed by computer simulations as the structure of Cu/Ni interfaces and consists of defects known as stair-rods and stacking faults. The computer models also indicate that this structure is very resistant to deformation. Theoretical Strength - Deformation in Nanostructured Metals Cu Ni Cu Ni As-deposited Under applied strain3-D view of the interface structure Computation studies shed light on the role of defects in controlling ultimate strength in solids. DMS&E Mechanical Behavior CRA

k || -resolved contributions from Fe(001) minority states to the STM current (n 1 ) and corrugation (n 2 ) for different applied fields. Yellow (red) denotes positive (negative) values. Charge density above the Fe(001) surface showing the anticorrugation for an applied electric field. Scanning Tunneling Microscope data are normally interpreted as directly giving the positions of the atoms on a surface. Calculations of the effect indicate situations where the electric field induced by the tip modify the electronic densities and give false indications for the atomic positions. New Ideas Underlie Experimental Interpretations Angular Resolved Photoemission experiments reveal the breakup of the Fermi surface in high Tc cuprate superconductor by forming pseudogap, starting at about 180K and reaching the isolated points for the superconducting state at 85K. That these points exist is strong evidence for the d-wave character of the superconductivity. The ability to see this detail was enabled by the theorist’s realization that one could characterize the energy dependence of the experimental data that made it possible to extract the information. Theoretical efforts allow interpretations of photoemission to reveal pseudogap in superconducting cuprate and account for tip effect in STM observations. DMS&E Theoretical Condensed Matter Physics CRA

Theory of Experiments To advance frontiers in computational materials science through strong coupling with table-top experimental efforts as well as at BES user facilities to benchmark theoretical models and to guide experimental designs. Theory vs. Experiment: silicon nanoclusters Excited State Electronic Structure Large Facilities Science Table-top Science Theory and Computation

CMSN Cooperative Research Teams Current Teams Under DMS&E Support  Excited State Electronic Structure and Response Functions: Louis, Rehr  Magnetic Materials Bridging Basic and Applied Science: Stocks, Harmon  Microstructural Effects on the Mechanics of Materials: Wolf, LeSar  Fundamentals of Dirty Interfaces: From Atoms to Alloy Microstructures: Rollett, Karma  Predictive Capability for Strongly Correlated Electron Materials: Scalettar, Pickett Potential Additions  Multiscale Studies of Formation and Stability of Surface-based Nanostructures The mission of the Computational Materials Science Network is to advance frontiers in computational materials science by assembling diverse sets of researchers committed to working together to solve relevant materials problems that require cooperation across organizational and disciplinary boundaries. Collaborative Programs to Tackle Complex Grand Challenges For more information on CMSN:

Materials Theory Institute (MTI)  A visitors program designed to attract leading scientists with expertise complementary to that available at the host institutions  Foster growth and expansion of theoretical science by catalyzing interdisciplinary interactions and collaborations  Format enables mobile, well focused, and highly interactive character research  Tackle a rich variety of the compelling and topical scientific problems that strengthen and expand the capabilities of the home institution  Regular workshops focused on the most urgent emerging topics to attract leading world scientists to advance the field and contribute to the creative and stimulating atmosphere of the Institute Collaborative Programs to Tackle Complex Grand Challenges DMS&E currently supports MTI projects at ANL and BNL

DMS&E recognizes many outstanding materials sciences issues could benefit considerably from high-end computing.  Access to high-end computer resources is a limiting factor for DMS&E researchers.  Reliability of time allocation over a period of several years is critical for optimum design of computation strategies. Availability and Access to DMS&E Computational Resources DMS&E is pursuing options to Seek further resource allocations within Office of Science/ASCR Leverage resources at other computer centers (e.g., NSF Centers) Expand DOE Centers Provide additional clusters

Software as Shared Research Infrastructure  Hyperdynamics and other multiple time scale techniques  Geometric Cluster Algorithm (GCA) for complex fluids simulation  Linear Expansion of Geometric Objects (LEGO)  Inverse band structure methods  Solving for many electron wave functions  Shared software and codes in CMSN Collaborative Research Teams Current efforts in algorithm and technique development: Compelling future needs to develop new algorithms and codes for general use at DOE’s leadership-class computing facilities GCA yields several orders of magnitude efficiency improvement of complex fluids simulations Bridging intermediate steps to incorporate the effects of rare but critical events into dynamic simulations Expansion of Complex Solids enables wide search for lowest energy structures using search algorithms

New Avenues to Computation  Spintronics – dissipationless spin currents  Quantum Computing – magnetic molecules & entangled states x: current direction y: spin direction z: electric field GaAs An equivalent to an “Ohm’s law” was discovered for quantum spintronics- Spin current can be induced by the electric field thru the spin-orbit coupling, and it can flow without dissipation! Science 301, 1348 (2003) ►Theoretical effort expanding on using spin as the mechanism of quantum computing and showing the spin-orbit coupling can help rather than being only a loss mechanism. ► Starting a project based on using the spin resonance of N isolated and positioned by an enclosing C 60 molecule.

 Increase support for investigators at universities and labs – particularly in nanoscience, correlated electrons systems, defects in solids, electronically excited states  Provide additional computer clusters  Encourage theorists and computer scientists to work with facility users and other experimental efforts  Expand collaborative efforts  Enhance usage of high-end computers  Support develop new algorithms and codes for general use  Support research in new forms of computing (spintronics, quantum computing) Outlooks for Theory and Computation in DMS&E The DMS&E FY2006 Budget includes an increase of $3M for theory and computation in nanoscience.

DMS&E Challenges and Strategies in Theory and Computation Challenges:  Build a “properly balanced” program under resource constraints  Maintain a coherent basic unity of theory, computation and experimental activities Investment Strategies  Seek close coupling with nanoscience  Influence BES User Facilities to enhance support for theory and computation  Expand efforts through new funding opportunities (e.g., Hydrogen Fuel Initiative)  Contribute to and take advantage of BES strategic growth areas (i.e., ultrafast science, energy security research)

Thank You! Thank You! The report reinforces DMS&E investment strategies and will guide our future theory and computation activities.