Paulette Clancy - US grants

An equipment grant is provided to upgrade the computer facility within the School of Chemical Engineering at Cornell University. The VAX-Cluster will have a significant effect on research projects in the areas of thermodynamics, materials processing, fluid mechanics, biochemical engineering and catalysis. The availability of the proposed equipment will be particularly significant for the following three projects, which are likely to be the heaviest users of the new system. In the area of thermodynamics and surface properties of fluids, theoretical studies are concerned with the development of new equations of state for fluids using perturbation and mean-field theories and computer simulations which will enable the calculation of solid and fluid properties from a molecular-level treatment. In the area of materials processing, non-equilibrium simulations of rapidly cooled interfaces are being performed to study the thermodynamics, structure and kinetics of the dynamic solid/melt interface produced by laser heating, for example. In the area of fluid mechanic, studies are being made of the flow of suspensions through branched conduits where the size of the particles is comparable to that of the channel. In the area of thermodynamics, the simulations are being used to investigate new phenomena for which no experimental data exist, for example, in the study of nucleation and small drops. The first study showing spontaneous phase separation in a pore and the existence of a capillary critical point different from that of a bulk fluid is now available. In the area of materials processing, the simulations provide fundamental understanding of the detailed motion and properties of rapidly moving solid/liquid interfaces not available elsewhere. The velocity temperature time profile can be produced theoretically, whereas experimentally, the instantaneous temperature is virtually inaccessible. Insight into the reasons for increased dopant segregation coefficients at the interface is also possible through simulation, though much less readily available through current theories or experiment. In the area of fluid mechanics, novel models accounting for the finite size of the particles are being developed where the asymptotic approximations of traditional theories are no longer valid and the hydrodynamic interactions between the particles and the wall become important. Thermodynamic studies of surface properties are applicable to many purification and separation processes including the removal of unwanted carbon dioxide and hydrogen sulfide from natural gases, and separations for hydrocarbons including xylenes and aromatics. The studies of pores are applicable to capillary permeability in tight sands. Other projects are applicable to surfactant behavior. The materials processing studies are applicable to a wide range of rapid solidification techniques including laser annealing, laser glazing and ion implantation. The fluid mechanics studies are a prototype for a broad range of techniques such as filtration and chromatography. One application under study is that of cell motion in microcirculation. The studies can also provide insight in the design of new separation processes, e.g. enhanced oil recovery. Support is recommended at the level of $50,000 in FY 1987 for partial support of a VAX-Cluster System.

This award will enable Prof. Keith E. Gubbins and colleagues at Cornell University to collaborate with Prof. K. Nakanishi and co-workers at Kyoto University, Japan, over a period of two years. They will continue a cooperative research program which has advanced the use of computer simulation techniques to investigate the thermodynamic properties of fluids and mixtures of fluids, as well as their structural properties at the molecular level. The techniques to be used involve statistical (Monte Carlo) and more classical analytical computer solutions of the equations of molecular dynamics. The purpose of this research is to make possible the reliable prediction of the physical properties of fluid mixtures, such as those involving natural gas and petroleum, that are used in industrial and other chemical processes. The fluids studied here will be those which associate strongly, such as alcohol and water. The phase equilibria of such mixtures are so complex that no satisfactory theory for them has been available. Computer simulations will be performed to study the thermodynamic, phase equilibrium, and dynamical properties of the bulk phases of these aqueous solutions, and the work will then progress to a study of the adsorption of associating molecules at phase interfaces. This research may lead to significant improvements in production, processing, and separation methods.

The research is aimed at elucidating the behavior of various doped silicon-germanium alloys during rapid melting and solidification. The emphasis is on understanding the kinetic and thermodynamic behavior of rapidly moving interfaces, and the mechanisms by which phenomena such as crystal nucleation, crystal growth, and solute trapping occur. Laser melting and solidification are being studied. Characterization techniques include transient conductance, transient reflectance, transmission electron microscopy, and Rutherford Backscattering spectroscopy. Non-equilibrium molecular dynamics is being used to model the structure.

Research programs in the areas of thermodynamics, biophysics and materials processing make extensive use of interactive computer graphics to help analyze computer simulation data by a visualization of the physical processes at work. Most of the projects use an atomic-level description of the physical system coupled to an appropriate statistical mechanics-based simulation technique (Molecular Dynamics or Monte Carlo) to produce files containing the positions of all the atoms or molecules in the system. These data files are then analyzed using interactive computer graphics. The impact of a computer graphics analysis strongly influences projects such as the design of liquid crystalline polymers, the stability of proteins against denaturation and the design of new materials such as rapidly solidified metal alloys, as described in the proposal. In a number of applications, particularly interfacial phenomena, the ability to make a videotape of the process is invaluable. Interfacial phenomena may involve capillary condensation in pores, membrane fusion or Molecular beam Epitaxy of semiconductor materials, but all profit by the visualization offered by an approximation of real-time motion of the substances under different conditions. High- performance graphics workstations linked to an appropriate video imaging system are used to bring about this visualization.

This award will facilitate continued cooperation between chemical engineers at Cornell University and Kyoto University. The project is part of a larger project in the field of molecular thermodynamics that includes research on fluids by means of the methods of statistical mechanics and computer simulation. In previous research conducted by the two groups, the effect of molecular association on the properties of associating fluids has been studied by simulation for simple and realistic potential models. This project will focus on studies of water and aqueous mixtures. In particular, the scientists will carry out investigations on theoretical and simulation studies of water-methanol mixtures; molecular dynamics simulations of the behavior of water in microporous materials, including carbons, silicas, and clays; and simulations of rapid cooling in polyol-water mixtures. The Cornell group, led by Professor Keith E. Gubbins and Professor Paulette Clancy, will provide expertise in the theoretical methods and simulation techniques for studying micropores and rapid cooling. The Japanese group, under the leadership of Professor Koichiro Nakanishi, has complementary expertise in developing intermolecular potential models for these systems and in molecular dynamics techniques applied to aqueous mixtures. The long term aim of the research project is to understand fluids and fluid mixtures of associating molecules (involving H-bonds, charge-transfer complexes, etc.) in detail at the molecular level. The approach has been based on the use of fundamental statistical, mechanical, mean-field and perturba- tion theories, as well as Monte Carlo and molecular dynamics computer simulations. The simulations are used to test the theoretical predictions for a well-defined potential model, and also to investigate phenomena that are difficult or impossible to study by experiment.

9520315 Teter This award is one made through the FY95 Computational Approaches to Real Materials competition. Funding is provided through the Divisions of Materials Research, Mathematical Sciences and Advanced Scientific Computing, as well as by the Office of Multidisciplinary Activities in the Mathematical and Physical Sciences Directorate. The research combines algorithm and code development with materials theory to address important materials problems for which computational breakthroughs can produce large payoffs. As such, the research spans the strategic initiatives in High Performance Computing and Communications and Advanced Materials and Processing Phase transformation and electronic structure properties of realistically modeled crystalline and amorphous materials will be studied using a new tight binding molecular dynamics code. This new technique represents a compromise between computationally infeasible ab initio techniques and faster - but less accurate - methods that employ classical potentials. The tight binding molecular dynamics method has non-orthogonal basis functions and handles electrostatic interactions. This will allow the study of inhomogeneous systems such as amorphous materials and interfaces, as well as ceramic materials which have significant ionic character in their bonding. The method will build on previous linear scaling techniques which are explicitly parallelizable. The codes will be implemented on the Cornell SP-2. This new technique will allow the study of a variety of physical systems and processes, inaccessible by previous methods, such as solid/liquid and solid/solid phase transformations, defect diffusion in materials and amorphous materials. Besides Cornell, the team includes participants from Corning, Los Alamos National Laboratory, Oxford University, AT&T Bell Laboratories, IBM and DEC. %%% This award is one made through the FY95 Computational Approaches to Real Materials competition. Funding is provide d through the Divisions of Materials Research, Mathematical Sciences and Advanced Scientific Computing, as well as by the Office of Multidisciplinary Activities in the Mathematical and Physical Sciences Directorate. The research combines algorithm and code development with materials theory to address important materials problems for which computational breakthroughs can produce large payoffs. As such, the research spans the strategic initiatives in High Performance Computing and Communications and Advanced Materials and Processing The research will involve a complementary team who will apply fundamental aspects of materials physics to understand and simulate the large scale processing of materials. Such processing phenomena as solid/solid phase transformations and solid/liquid phase transformations will be modeled. In addition, the simulations will be large enough so that the effects of defects and their kinetics will be studied. The use of new algorithms and their implementation on massively parallel computers enable these ambitious calculations to be done. The results will be a major contribution to the design and processing control of new materials. ***

A set of multimedia modules ia being developed and is designed for use in core chemical engineering undergraduate courses (e.g., thermodynamics, fluid mechanics, process design and control). Each module typically consists of digital video, sound, animation, and text and stresses the connection between a traditional mathematical representation (e.g., as seen in textbooks) and a laboratory experience. These modules are being developed with Macromedia's "Director" package on PowerMacintosh machines. Each completed module can be placed on the World Wide Web by way of the client Mosaic for easy access by other educators.

This work involves AB intitio simulation studies for semiconductor materials processing. The project will provide the most careful test to date of the ability of approximate ab intitio tight binding models to predict the processing conditions necessary to produce desired materials properties. In particular, the PI's will study promising new dopants like Ga and In (to replace boron as a p-dopant) for semiconductor materials like Si and SiGe. This will involve a combination of simulation techniques (molecular statics, Molecular Dynamics and Kinetic Monte Carlo) to produce dopant diffusion profiles. The tight binding results for energies of formation and mobility of dopant species will be used in a continuum code to leverage the atomic-scale results to macroscopic scale properties. They will also investigate the role of stress, say at an SiGe/Si interface, to enhance lateral diffusion in a semiconductor device. The studies here, computer simulation of dopant diffusion in Si-rich materials, are crucial to the semiconductor industry aiming for sub-100nm device features in the 21st century. Close collaboration with local experimentalists and nearby industries will allow planning and execution of complementary experimental studies of these simulations.

9980100
Clancy
This is an award under the KDI initiative that is managed by DMR and CTS. The PIs seek to describe structural and dynamical order during a phase transformation. This order can range over the continuum between perfect order of a crystalline material and the nearly total absence of long-range order of the amorphous phase. The large dimensionality needed to represent the total dynamical order of a system will be reduced to a small set of parameters to define the possibility of a transformation between phases. Unified models will be provided which define a set of order parameters that can be applied to materials with various levels of order; an accuracy of distinction between phases of more than 90% will be attempted. Test bed materials are both organic (small rigid thiophenes that are ideal for comparison to simulation studies) and inorganic (various morphological forms of silicon). To model these accurately and to make large-scale dynamical simulations needed to study order transformations, a new quantum mechanical algorithm will need to be developed to allow calculations with at least the speed and accuracy of current tight-binding methods. The PIs propose to develop such a quantum mechanical algorithm based on the Harris functional and plan to incorporate Voter's hyperdynamic techniques to increase accessible simulation times. Reverse Monte Carlo techniques will also be used to develop a scheme for creating systems with a chosen extent of order.
Using this suite of linked simulation tools that can describe processes from nanoscopic to macroscopic length scales, the PIs will establish co-relation and phase transformation probability of these material models subject to processing conditions (thermal cycles, nucleation sites, plasma-enhanced precursors, etc.) The proposed simulation methodology will be tested on a solidifying interface structure, examining and understanding the roles of molecular architecture and inter-atomic potentials. Quantitative links will be developed that connect processing conditions and the resulting structure in complex materials. The critical point at which the final structure of the solid is predictable or controllable given a metastable starting point of known order.
%%%
This is an award under the KDI initiative that is managed by DMR and CTS. The proposed work constitutes a new computational challenge. Observing that the ability to tailor local and long-range structural order in materials is of great technological utility, the PIs seek to develop large-scale numerical simulation techniques that would be used to provide a fundamental description of structural order and processing in these materials. Work will be performed in conjunction with experiments on model systems of commercial interest. This work will contribute to the field of organic optoelectronics, creating polymers with controlled properties, in modeling the low-temperature processing of silicon, the integration of biosensors, and stacked 3D components. It will lead to a coupling of organic and inorganic systems for biosensors.
***

This proposal was received in response to the Nanoscale Science and Engineering Initiative, Program Solicitation NSF 01-157, in the NIRT category. The proposal focuses on developing novel chemical approaches to forming well-behaved and robust interfaces between small organic molecules and both conducting and insulating inorganic ultrathin films for applications in molecular scale electronics. Much of the success of present day microelectronics is due to the ability to integrate a variety of (mostly) inorganic materials into structures useful for devices. For example, silicon dominates the field not because of its intrinsic electrical properties, but because of the quality of the interfaces it forms (e.g., the Si-Si02 interface). The work to be conducted here seeks to develop organic-inorganic interfaces possessing equivalent or superior properties, where small organic molecules form the active layers. The solution lies in the development of chemically based approaches to the formation of the critical interface between the inorganic layers (both metallic and dielectric) and the organic layers. Success in this venture will require the application of sophisticated synthetic organometallic chemistry, surface and interface science, self-assembly and nanofabrication, and "chemically accurate' computer simulation. The team that has been assembled at Cornell possesses expertise and significant experience in all of these areas. The organic layers will typically be formed by a process of self-assembly (in solution or in vacuo) on substrates that have been patterned to expose selected areas comprised of metal (e.g., Au), oxide (e.g., Si02), or nitride where the self-assembled monolayer will bind. Study of patterned substrates is vital for the investigation of a number of issues, from the fundamental to those related to device design and performance. Ultimately the team seeks as a final set of goals: (i) development of novel organometallic precursors for the formation of both conducting and insulting layers that will interface seamlessly with the organic layer; (ii) development of a fundamental understanding of the interface formation process, including the effects of process variables such as temperature on the molecular scale structure of the interface; (iii) demonstration of controllable device properties for molecular scale electronics, given enhanced knowledge of the interfacial chemistry and physics; and (iv) development of computer models that can both predict the atomic scale structure of the interface, and the resulting electronic properties. A final significant challenge put forward by the Cornell team will be the development of a workshop on research ethics. From the experience of working to develop this workshop the participants hope to build a better understanding and recognition of responsible research conduct, and to know the relevant philosophical underpinnings of ethics sufficiently well to be able to make ethical choices in both the development and practice of their research.

This Integrative Graduate Education and Research Traineeship (IGERT) award supports a graduate training program at Cornell University in a highly interdisciplinary area of materials research that is central to advances in many areas of science and technology - the nanoscale control of surfaces and interfaces. This program provides doctoral students drawn from seven academic disciplines with hands-on, interdisciplinary training in the experimental and theoretical techniques necessary for forefront research at the nanoscale. The program is based on a dynamic, student-centric educational framework that transitions students from the coursework-based educational model typical of K-16 education to the self-directed learning necessary for professional R&D environments. As an integral part of their training, students perform interdisciplinary research on topics as diverse as the production of single molecule transistors, the design of non-volatile memory, the development of "plastic" electronics, and the fabrication of ultrasensitive chemical and biological sensors.
This program addresses the national workforce needs in materials research documented by a recent National Academies study. The study identified the field of nanomaterials - the focus of this traineeship - as the area of most rapid growth globally. By educating a new generation of nanomaterials researchers and performing fundamental research in this rapidly growing area, this program increases U.S. competitiveness. The program also addresses the underrepresentation of women and minorities in the field of materials through direct partnerships with two Historically Black Colleges/Universities, a substantial recruiting program and an extensive undergraduate research program. IGERT is an NSF-wide program intended to meet the challenges of educating U.S. Ph.D. scientists and engineers with the interdisciplinary background, deep knowledge in a chosen discipline, and the technical, professional, and personal skills needed for the career demands of the future. The program is intended to catalyze a cultural change in graduate education by establishing innovative new models for graduate education and training in a fertile environment for collaborative research that transcends traditional disciplinary boundaries.

This project is awarded under the Nanoelectronics for 2020 and Beyond competition, with support by multiple Directorates and Divisions at the National Science Foundation as well as by the Nanoelectronics Research Initiative of the Semiconductor Research Corporation.

The research objective of this proposal is to design and synthesize structurally precise graphene nanoribbons (GNRs) and incorporate them into high-performance electronic devices. GNRs are narrow strips of single-layer graphene that have garnered considerable attention as a possible replacement for silicon in high-performance nanoelectronic devices. Exploring the full potential of GNRs has been hampered by their limited availability and poor control of their width and edge structure. The proposal involves a collaboration between researchers at Cornell University and Princeton University. This project involves the synthesis of precursor polymers and their oxidative annealing into GNRs. The effects of edge structure and doping levels on materials properties will be determined, and the effect of changing structural parameters on the fabrication and testing of transistor and sensor device performance of GNRs will be undertaken. Computational modeling to support both the synthesis and device fabrication will be accomplished using a variety of approaches from ab initio studies of the electronic properties to Molecular Dynamics and Kinetic Monte Carlo studies to determine the structural characteristics. The proposal also integrates several educational initiatives with the research efforts. A new national group called "Women in Nanoelectronics" will be formed as part of this project, and the goal of the group will be to attract young women to nanoscience disciplines. Graduate and undergraduate students will receive training in an interdisciplinary, collaborative research environment and will be encouraged to broaden their skills through exchanges among the Princeton and Cornell laboratories.

Computing using graphene nanoribbons, ultrasmall strips of matter comprised of a single layer of carbon atoms, has the potential to generate efficient, ultrasmall devices; however, many significant technical hurdles must be overcome to realize the benefits. The project addresses an important, longstanding problem in using graphene in electronics and will further our understanding of this technologically important material. Such work could impact industries that use microprocessors in their products, including computer, consumer electronics, automotive, etc.

PI Name: Paulette Clancy
Institution Name: Cornell University
Proposal Title: GK-12 Grass Roots: Advancing Education in Renewable Energy and Cleaner Fuels through Collaborative Graduate Fellow/Teacher/Grade-School Student Interactions
Proposal ID: 1045513

Cornell GK-12 Fellows from engineering and the physical sciences are researching new ways to create renewable energy sources (wind, solar, geothermal and biomass) and other creative ways to reduce our carbon footprint. The core and strength of this GK-12 project lies in the development of new materials for energy creation and storage that achieve high performance and remain environmentally benign. The project will place graduate students in these fields into classrooms in grades 6-12 and will leverage strengths in creating computational tools to design new energy materials, predict their properties, and work synergistically with experiments, to accelerate commercialization. Coupled with their research, Fellows will undertake a new educational program for developing communication skills that will be highly effective with diverse communities and provide a life-long societal benefit for the promotion of science.

The Fellows will share their passion for energy research with students in middle and high school, especially those in Onondaga Nation schools close to Cornell. An early project, requested by the Elders, involves Fellows, faculty, and school students designing and building a solar (thermal) greenhouse as a hands-on project that fits a culture of earth stewardship. Many of the projects are strongly visual and computationally based, making them suitable for use by many communities, including students with hearing challenges, allowing their creativity to be fully realized. Fellows will enrich their research skills in energy projects, especially biofuels, through visits to a partner university in India, where they will take part in hands-on experience at a sugar mill where need for energy production must be balanced against that for food.

New products and material processing methods often require the identification of novel materials that are stronger, lighter, cheaper, or better in some way. Searching for new materials with a trial-and-error approach can be expensive and often ineffective. With this award, new mathematical methods and computer software will be developed to accelerate materials discovery. The planned approach will narrow the available options to those that are most likely to succeed, making discovery of new materials and processes more reliable and less costly. Demonstration of the approach will be made for materials to be used in flexible organic solar cells, but the methods could also be amenable to materials for use in pharmaceuticals or to food additives.

A new optimal learning approach to materials design is planned that uses advances in Bayesian experimental design and machine learning to predict material properties from previous data and domain expertise, and to intelligently suggest physical and computational experiments that will provide information that is most supportive of discovery. These new mathematical techniques promise to greatly accelerate materials design, providing better materials more reliably and with less experimental effort. The approach will be demonstrated in the search for organic semiconductor materials over a set of existing candidates, solvent choices, and processing conditions, and integrate both physical and computational experiments in this search. The test case is an all-organic solar cell system of contorted hexabenzocoronenes (c-HBC), deposited on carbon nanotubes (CNT). This complex system involves issues including complexation between c-HBC and CNT at different processing conditions, etc., which provide a stringent test of optimal learning and computer simulation methods to predict the processing-structure-function triad. This approach is broadly applicable to a diverse set of materials design problems.

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professors Howard E. Katz and Paulette Clancy of the Johns Hopkins University are developing small organic molecules for use in doping of conjugated polymers. Conjugated polymers are carbon-based macromolecules that contain long chains consisting of alternating double and single bonds. When the double bond arrangements are changed by removing or adding electrons, positive and negative charges are created in the polymers that enable them to conduct electricity similarly to metals such as copper. Currently, conjugated polymers are the most important class of materials used for optoelectronic devices such as LED (light-emitting diode) screens in mobile devices and computers; also being used to protect such electronic components from outside electrical interference. In this research, systematic studies using a combination of experimental and computational approaches will closely examine the mechanism of electron transfer in these polymeric systems, a mechanism for which many details are still not known. Increased understanding of such systems has the potential to lead to novel conjugated materials with tunable electronic properties of relevance to flexible electronics and power devices. The education and outreach activities of this project will focus on the engineering innovation program at Johns Hopkins University targeting low-income Baltimore City participants. A boot camp on coding will be offered to middle schoolers with the goal of improving the programming skills of future STEM (Science, Technology, Engineering and Math) scientists, with the particular goal of reaching women and members of underrepresented groups.

This research is targeting a series of thiophene-based molecules and oligomers for use in doping of conjugated polymers. The proposed theoretical and experimental studies are designed to test the hypothesis that the free energy change from (a) difference in hole/electron affinities, (b) work of charge separation, and (c) delocalization/distribution entropy between neutral conjugated polymers and covalent ion-adducts will lead to charge transfer and electrical conductivity. Thiophene-based conjugated molecules and oligomers for adduct formation studies will be selected with a range of hardness/softness and to favor paired-electron, covalent bond formation (as opposed to electron transfer interactions) in aprotic solvents to enable testing of whether the covalent adducts ultimately serve as electron transfer agents of conjugated polymers. Extensive spectroscopic and electrochemical characterization methods are to be used to gain a deeper understanding of the doping mechanism and how structural changes affect doping levels, solid-state structures, conductivity, and the Seebeck coefficient. The results associated with this research have the potential to lead to more reliable doping strategies in conjugated polymer- a key challenge for further development of organic bioelectronics and flexible conductors.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.