Materials Day Agenda 2011

In the semiconductor industry, with the introduction of high-k & metal gate devices, materials have come to the forefront in addition to the transistor to enable Moore’s law of scaling. Computational Materials Design (CMD) is recently associated with the concept of designing materials in silico for real materials applications.  We will use specific cases in which CMD was successfully applied in synthesizing materials and in estimating properties.  In addition, we will focus on critically evaluating the gaps in what is preventing from a successful application of CMD similar to Computational Fluid Dynamics, Structural, or Mechanical Design.  We will conclude the talk by showing exciting opportunities for applications of chemistry, physics, and materials science in advancing the future generation of semiconductor process technologies.

One of the greatest challenges of the 21st century will be to understand, invent, and engineer new mechanisms and materials for energyproduction, energy storage and energy transport to counter the deleterious environmental and political impacts of our long-standing reliance on crude oil.  Current renewable energy conversion and storage technologies are too expensive, too inefficient, or both, substantially limiting their use and global impact. For example, over the last century wehave used two trillion barrels of oil and are likely to retrieve and use another trillion in the next several decades. The sun provides that entire 3 trillion barrels worth of oil energy – in just 2 days. And yet, tapping into this enormous power to generate electricity is the least utilized renewableenergy resource today. At the core of the energy challenge is a materials choice: many of the key mechanisms that convert and store energy are dominated by the intrinsic properties of the active materials involved. Our imperative is thus to predict, identify and manufacture new materials and designs as comprehensively and rapidly as possible, as the pressing challenge of producing and storingenergy renewably calls for game-changing leaps forward rather than our current path of incremental advances. Toward that end, we use efficient atomic-scale computational approaches that serve both to elucidate fundamental mechanisms as well as predict completely new concepts and solutions. Our research focuses on the prediction of key properties that govern the conversion efficiency in thesematerials, including structural and electronic effects, interfacial charge separation, charge traps, excited states, band level alignment, and synthesis approaches. Examples of such calculations in the areas of solar photovoltaics and solar fuels will be presented.

Design cycles of aircraft require a great deal of time and investment to even get to the stage of building large engineering structures to be tested.  Powerful analysis and simulation techniques such as computational fluid dynamics, finite element methods, and computer modeling are taking prominent roles to reduce this design cycle. The materials engineering community is now challenged to engage through ICME.  This presentation reflects on design cycle changes over the last few decades and brings new insights on the ability to model and test at various size-scales – from the nano scale to large structures. Validation testing and advanced simulation are essential elements in the chain of events that are required to go from concept design, to the process development, to the manufacturing phase, and finally to product certification.

This talk will explain how materials in biology are synthesized, controlled and used for a variety of purposes—structural support, force generation, catalysis, or energy conversion—despite severe limitations in available energy, quality and quantity of building blocks.  By incorporating concepts from chemistry, biology and engineering we describe how computational materials science has led the way in identifying the core principles that link the molecular structure of proteins at scales of nanometers to physiological scales at the level of tissues, organs, and organisms. We demonstrated that the chemical composition of biology's materials plays a minor role in achieving functional properties. Rather, the way components are connected at different length-scales defines what material properties can be achieved, how they can be altered to meet functional requirements, and how they fail in disease states. We have achieved this by using the world’s fastest supercomputers to predict properties of complex materials from first principles, in a multiscale modeling approach that spans many orders of magnitude in scale. This method, combined with experimental studies, allows us to build virtual “in silico” material models that provide unseen insight into the workings of natural and synthetic materials from the bottom up.

We demonstrate this approach in a case study of spider silk, one of the strongest yet most flexible materials in Nature, despite being made out of some the simplest, most abundant and intrinsically weak proteins, including weak hydrogen bonding. We discovered that the great strength and flexibility of spider silk—exceeding that of steel and other engineered materials—can be explained by the material’s unique structural makeup that involves multiple hierarchical levels from the nano- to the macroscale. These hierarchical levels span from the genetic information that defines the protein sequence to the structural scale of an entire spider web. Each level contributes to the overall properties, but the remarkable properties emerge because of the synergistic interaction across the scales where the sum is more than its parts. This concept explains how spider silk provides extreme functionality despite the simple basis in its makeup. By translating this insight gained from the study of natural materials such as spider silk to engineered materials such as carbon nanotube fibers, graphene composites or metal-polymer films, our research has resulted in an engineering paradigm that facilitates the design of sustainable materials starting from the molecular level, leading to the formation of hierarchical structures that span all scales from nano to macro, and leading to a merger of the concepts of structure and material.

We illustrate this concept by drawing an analogy to a seemingly far and distant field—music. Reminiscent of protein materials, the integrated use of structures at multiple scales is the key to provide superior functional properties despite limitations in available building blocks, a set of musical instruments such as piano, violin or cello. In music, tones are played at different pitch, accentuation or duration and then assembled into melodies. The collective interaction of melodies, played by different instruments and arranged in a particular way, eventually results in the powerful expression of a symphony.  We discuss analogies with other biological materials such as collagen in bone, or intermediate filaments in cells, and present general approaches towards the design of adaptable, mutable and active materials. Our work enables a paradigm shift in the design of materials that exceed the properties of natural ones while being constructed with low energy use and from abundant and intrinsically poor material constituents.

Dramatic improvements have been made in computational techniques at different scales in the past few decades. Recently, by transferring parameters, equations, and insights obtained from smaller scale to larger scale, the combination and overlapping of these techniques bring material modeling into a truly multi-scale era. In this presentation, I will briefly overview how computational materials modeling were integrated with light weight and energy storage materials’ research in automobile industries with examples. In one case, first principles calculations were integrated with cohesive zone and growth chemistry models to predict interface adhesion and growth stress of  nano-crystalline diamond (NCD), in order to enable it as a tool coating for aluminum machining.  In the second case, a coarse-graining approach was developed to obtain the morphologies of hydrated Nafion for fuel cells, where the network connectivity of hydrophilic domains strongly influences the proton conductivity and mechanical property of the membrane. In both cases, material modeling did not stop at explaining existing data or confirming experimental findings, but to make an experimentally testable prediction on how to optimize material structures and processing conditions before material synthesis.

The need for novel materials is the technological Achilles Heel of our strategy to address the energy and climate problem facing the world. The large-scale deployment of photovoltaics, photosynthesis, storage of electricity, thermoelectrics, or reversible fuel catalysis can not be realized with current materials technologies. The “Materials Genome” project, started at MIT, has as its objective to use high-throughput first principles computations on an unparalleled scale to discover new materials for energy technologies.  Only computationally driven materials design can deal with the scale and urgency of the materials discovery problem.  I will show how several key problems such as crystal structure prediction and accuracy limitations of standard Density Functional Theory methods have been overcome to perform reliable, large scale materials searching.  

Successful examples will be shown of high-throughput calculations in the field of lithium batteries, several new materials that have been discovered and discuss developments in other fields.  In addition, the public release version of the Materials Genome project which will be making large quantities of computed data freely available to the materials community will be shown.

Soft materials are materials in which bonds between molecules are weak non-covalent bonds. Some natural examples are DNA, proteins, and biological membranes. These molecules have existed in our world for millions of years, and are the basis of life as we know it. Only during the last century, however, has mankind developed methods to synthesize polymers that resemble their biological counterparts. These polymeric soft materials, colloquially known as plastics, have revolutionized our world due to their outstanding properties that can be tailored for a wide variety of very specific needs, ranging from ultra high strength fibers to organic light emitting devices to biomedical devices. Soft materials thus represent a promising field of interdisciplinary research where computational material science can have a powerful impact by opening new frontiers in which previously unthinkable behaviors are now possible.  In this talk I will highlight some of the “smart” emerging properties of different classes of soft systems studied in our research group. In particular, I will present our work in different systems in which responsive soft materials present interesting and promising phenomena that could have strong implications in future technologies. The systems that I will talk about range from directed block copolymer assembly to blood clotting and self-healing materials. In all cases, external fields in the form of confinement or flow dictate the state of the system, offering a new way to tailor the properties of these materials. Emphasis will be placed in the important role that simulations can provide in understanding and designing such systems.