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How Do We Control Material Processes at the Level of Electrons? Progress on Grand Challenge New Horizons for Grand Challenge Remaining ChallengeRefreshed.

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Presentation on theme: "How Do We Control Material Processes at the Level of Electrons? Progress on Grand Challenge New Horizons for Grand Challenge Remaining ChallengeRefreshed."— Presentation transcript:

1 How Do We Control Material Processes at the Level of Electrons? Progress on Grand Challenge New Horizons for Grand Challenge Remaining ChallengeRefreshed Grand Challenge? Does enough remain to be grand? Yes; further questions based on the fundamental issues still remain, but with different directions and applications than previously existed or explored. Significant progress has been made to several of the questions on a fundamental level, contributing to the expansion applications. Is it tractable on the decadal scale or longer? Yes; addition of new questions based on the quantum control of electrons in atoms, molecules, and materials would be increase the scope of the challenge and would add to the comprehensive understanding and level of control for more applications. What parts of the Grand Challenge have been solved? Computational techniques have improved and now can model larger molecules more quickly. Molecular dynamics has allowed the quantum mechanical calculation of reaction landscapes much more quickly and accurately to discover accessible transition state pathways depending on the reaction conditions and excited states of the reactants and intermediates. On an experimental and computational level, the study of plasmonics has contributed to understanding light induced excited states (featured as a focus area in Nature Photonics focus in Nov 2012). Quantum coherence and dynamics with respect to superconducting qubits, quantum transport in quantum dots, and in light harvesting is much better understood (DOI: /srep00885 and references therein.) Has the focus/scope of the Grand Challenge evolved? Challenges remain in using computation to quantitate properties for larger length scales in materials and predict/explain their reactivity. Also, developments are necessary to move beyond Newtonian based molecular dynamics to accelerated dynamics that can more quickly map potential energy landscapes for more complicated reactions (also useful for Challenge #5). This can assist the accurate representation of reaction pathways that occur at varying temperatures or with reactants in higher energy excited states. The experimental measurement of thermodynamic parameters in different solvents has assisted improved solvation models in quantum mechanical models, but still needs to be refined further. Is a new statement of the Grand Challenge needed? Yes; the questions answered by the past decade of research has spawned new directions in areas that are still not well understood. A new statement could encompass these new challenges and directions. For example, understanding the electron dynamics in light harvesting and photosynthesis has made significant progress, but this is less well understood in electrode materials and heterogeneous catalysis, as well as other materials in the nanoscale. Should the Grand Challenge be retired? No, it should be restated/expanded, as described above. Submitted by: Jenny Yang Affiliation: University of California, Irvine

2 How do we design and perfect atom- and energy-efficient synthesis of revolutionary new forms of matter with tailored properties? Progress on Grand Challenge New Horizons for Grand Challenge Remaining Challenge Refreshed Grand Challenge? Does enough remain to be grand? Yes; although significant progress has been made, directed level of control for complex atom and energy efficient synthesis has yet to be achieved. The use of tailored micro-scale environments to promote selectivity and influence reaction pathways under mild conditions is just beginning to be explored. Much of these advances will require improved techniques to examine reactions in situ, especially on surfaces. Additionally, the use of non-thermal methods such as light or electrochemical potential to drive “uphill catalysis” or form meta- stable forms of matter has expanded but not reached its full capabilities. More complicated problems such as reducing biomass to liquids or stimulus control of materials has presented more challenges. Is it tractable on the decadal scale or longer? Given the progress that has been made since the original report, great strides can be made on the decadal scale for atomic level control of new materials and catalysts. What parts of the Grand Challenge have been solved? Soft materials: Progress has been made towards catalytic design via first principles, especially combining experiment with theory and correlating reactivity and thermodynamic properties with function; however, only the most basic reactions (i.e. hydrogen evolution reaction) have been described thoroughly at this point. Catalyst considerations have been described for cascade reactivity (i.e. CO2 to CH3OH, relevant to artificial fuel production, DOI: /ja208760j). Elegant solutions for self repair in polymers have been demonstrated (DOI: /ja ), but primarily for soft materials using weak interactions. OLED have now achieved commercialization for a variety of applications. Hard materials: The use of quantum mechanical methods and experiment to understand heterogeneous catalysis has assisted in the identification of catalytic active sites, whether they are edges, specific faces, or defects. This has contributed to the development of new synthetic methods to target materials with a greater density of catalytic active sites. Has the focus/scope of the Grand Challenge evolved? Soft materials: Many small molecule transformation with homogeneous, heterogeneous, and enzymatic catalysts follow similar modes of activation, and selectivity often emerges through common intermediates. These shared themes are just beginning to emerge, and the use of computational and experimental tools has greatly improved the understanding of critical intermediates and how they can be stabilized by the catalyst. An example of this is the use of activity descriptors, initially used for heterogeneous catalysts, being applied for homogeneous catalysts and enzymatic active sties. Some of the initial studies on cascade catalysis has described the problem of designing catalysts that are tolerant to the same conditions to allow one-pot catalysis. Hard materials: New methods of non-thermal synthesis will promote formation of meta-stable phases that are predicted to have unique properties. Is a new statement of the Grand Challenge needed? A new statement would unite common themes in the reactivity and intermediates discovered in catalysis by heterogeneous, homogeneous, and enzymatic active sites. This could lead to the development of hybrid catalysts that incorporate micro-environment or bi-functional capabilities necessary to control and direct electron, proton, and atom transfer events. Additionally, as some of the materials challenges have made great advances (such as OLEDs), new desirable properties in soft and hard materials could be proposed. Should the Grand Challenge be retired? No, the current state of the research presents new opportunities for fruitful cross disciplinary advances to achieve the primary goals.

3 How do remarkable properties of matter emerge from complex correlations of the atomic or electronic constituents and how can we control these properties? Progress on Grand Challenge New Horizons for Grand Challenge Remaining ChallengeRefreshed Grand Challenge? Does enough remain to be grand? Yes, but the challenges with electron correlation in materials seem like they may fit more appropriately into other grand challenges (#1, 2, & 5), especially given the need for improved methods of material synthesis, experimental methods, and theoretical models. Some issues with bio-complexity and evolution far from equilibrium may also fit into grand challenge #5. Is it tractable on the decadal scale or longer? Yes; any of the fundamental properties may be tractable. Greater computational modeling /instruments for biological correlation behavior would be beneficial to many other areas of biophysical research. What parts of the Grand Challenge have been solved? The understanding of high temperature superconductors appears to have made steady progress, although I am not very familiar with the field. Work on correlated properties in heterostructures, particular for quantum dots has been exciting in the context of quantum dot photovoltaics. I am not familiar enough with correlation in soft matter or biological systems to comment. Has the focus/scope of the Grand Challenge evolved? Many of the challenges associated with electron correlation in materials would work synergistically with the research working towards grand challenge #1. However, the focus on collective phenomenon in super-fluids and Bose-Einstein condensates, and biology remain relevant. Is a new statement of the Grand Challenge needed? Yes; the current challenge represents diverse fields of research, some of which may benefit more from inter- disciplinary work encompassed within other challenges Should the Grand Challenge be retired? Possibly; emergent phenomenon in condensed matter physics and biology should will answer many fundamental questions important to other fields, but not sure if this should be a grand challenge itself.

4 How can we master energy and information on the nanoscale to create new technologies with capabilities rivaling those of living things? Progress on Grand Challenge New Horizons for Grand Challenge Remaining ChallengeRefreshed Grand Challenge? Does enough remain to be grand? Yes, the original challenge was very ambitious, and the tools necessary to advance the research have now been developed. The growth of the field is rapid, and the fundamental science involved has the potential to span many different scientific areas and used for many different applications Is it tractable on the decadal scale or longer? Yes, many of the fundamental questions will progress quickly with the development of new analytical tools. What parts of the Grand Challenge have been solved? The first part of the grand challenge described the need for advances in microscopy and other experimental or analytical tools to examine cells and other biological material at the nanoscale in situ. There has been significant progress in both optical microscopy and scanning probe techniques (DOI: /j.biocel , DOI: /nnano ). The development of wave guiding materials will also add to the toolbox of studying cells at greater resolution. Additionally, the challenge of synthetic immunology, or communicating to cells directly via chemical signals to tailor and direct immune responses, has begun to be addressed in earnest (DOI: /nchembio.477, DOI: /j.tibtech ). Advances have been made in understanding photon-chemical coupling, but the interface and charge transport from photo-absorbers and delivery to catalysts or architectures that can utilize the energy is still poorly understood. Has the focus/scope of the Grand Challenge evolved? Synthetic immunology has described new methods to replicate the chemical signals that are used in natural cell communication. Expanding these discoveries to other cell responses would be an entry into biological communication for a variety of applications. Additionally, although microbial fuel cells or hybrid energy conversion devices is an old idea, recent studies (DOI: /j.rser , DOI: /c1ee02531g) have reinvigorated the field and modern tools can be used to provide more detailed information about interfacial electron transfer. Additionally, new directed evolution techniques can be used to optimize microbial response and function. Coupling microbes to electrodes provides an opportunity to interchange chemical and electrical energy efficiently, and even coupling wastewater oxidation/cleanup with fuel generation (DOI: /s ). These types of electricity-chemical interchanges are also necessary to obtain a better understanding of natural photosynthetic pathways. Is a new statement of the Grand Challenge needed? Yes, the specific challenges (relating to synthetic cell communication and hybrid bio-electrode materials) could be expanded, and new experimental or computational tools that would advance the research could be described. Should the Grand Challenge be retired? No, although the ultimate goals are ambitious in scope, these are important areas of research and the potential for game-changing advances is high.

5 How do we characterize and control matter away - especially very far away - from equilibrium? Progress on Grand Challenge New Horizons for Grand Challenge Remaining ChallengeRefreshed Grand Challenge? Does enough remain to be grand? Yes; although this problem has been studied for a long time, the complexity of the problems and potential importance in many different fields should maintain it’s status as a grand challenge. Is it tractable on the decadal scale or longer? Many of the tools (particularly more advanced computational power for modeling systems, and single molecule spectroscopic tools) are just being developed; the use of these will contribute to tangible advancements on the decadal scale or longer. What parts of the Grand Challenge have been solved? Many advances have been made in modeling atmospheric chemistry, a classic example of a non-equilibrium system, although the complexity of the system has contributed to an incomplete picture. Heat transfer, particularly to oceans, is still a problem. New tools have been developed to measure molecular dynamics for single molecules (DOI: /nphoton ), and single molecule catalysis by enzymes (DOI: /science ) and will contribute to understanding their activity to ensembles in statistical mechanics. The application of the concept of jamming has been applied to protein folding in biological systems (DOI: /ncomms2177). New catalytic activity by meta- stable natural minerals (in this case, formed under hydrothermal conditions) have been explored recently (DOI: /pnas ). Some methods for increasing minority carrier diffusion lengths in photovoltaic materials have been answered. (DOI: / ) Has the focus/scope of the Grand Challenge evolved? New methods of synthesis (primarily non-thermal) are required to generate meta-stable phases of matter. For example, targeted synthesis can be coupled using experiment and theory to maximize the concentration of site most likely to display catalytic activity. An example of this is the edge sites of MoS2 display the highest activity for electrocatalytic hydrogen evolution, but is a higher energy configuration. New synthetic methods that utilize electrochemical or photochemical methods would avoid thermal equilibrium in the synthesis of meta-stable materials (i.e. Cu for CO2 reduction electrocatalysis, DOI: /nature13249). Biological mechanisms often utilize very small amounts of energy to achieve transformations under ambient conditions that can currently only be replicated using high heat and pressure (i.e. N2 reduction to ammonia). This is another area where non-equilibrium effects can be utilized to improve catalysis. The development of improved accelerated dynamics computational methods (also suggested in Challenge #1) will improve descriptions of energetic landscapes and facilitate identification of local minima. Is a new statement of the Grand Challenge needed? Possibly, to incorporate more applications and utilization of some of the new experimental and computational tools. Some of the challenges related to synthesis of meta-stable materials is also covered in Challenge #2. Should the Grand Challenge be retired? No, the discovery of fundamental rules to non-equilibrium systems are too important and ubiquitous to nearly all scientific fields.


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