- Modeling of Organic Reaction Mechanisms
- Modeling Self-Assembly
- IBM Research Almaden ARC ANGELS Student Seminar Series
Dr. Spike Narayan
Science & Technology
"Mind, like a parachute, works best when open"
"Any sufficiently advanced technology is indistinguishable from magic."
- Arthur C. Clarke
"If we knew what it was we were doing, it would not be called research, would it?"
- Albert Einstein
Almaden Institute 2012 : Superconductivity 297K
Science and Technology welcomes researchers from academia and industry to present their work in Almaden's Science Colloquium Series.
Science and Technology staff who are interested in inviting researchers for this series are encouraged to contact Gavin Jones (email@example.com) or Greg Wallraff (firstname.lastname@example.org) to arrange presentations.
Topic: Size Matters: The Importance of Building Things Small
Speaker: Julia R. Greer (California Institute of Technology)
Date: 1/14/2015 Time: 4:00 PM - 5:00 PM
Location: Auditorium A
Abstract: Professor Greer’s research group develops new ways to synthesize nanostructured metamaterials via cellular architectures and hierarchical design principles. They focus on the internal critical microstructural length scale of materials in studying mechanisms governing mechanical deformation, where competing material, and structure, induced size effects drive overall properties. Many of those materials have micro-lattice and micro-truss architectures with the potential to scale up their desirable nanoscale properties. Their synthetic schemes extend to a wide range of material classes, including metals, ceramics, and semiconductors.
Her lab’s specialized tool - a miniature probe that manipulates and deforms tiny material samples inside a monitoring scanning electron microscope - documents nanomaterial response to mechanical perturbation at different temperatures and deformation rates. By decoupling properties like strength and density a variety of applications are enabled, from ultra-lightweight batteries to damage-tolerant cellular solids and artificial cell scaffolds.
Professor Greer's Ted Talk:
Another specialized tool in Professor Greer's life is the piano. She is an accomplished concert pianist and might be coaxed into performing in the auditorium following her talk.
Topic: Using High-throughput Computation to Design Next-generation Batteries and the Materials Project Electronic Structure Database
Speaker: Anubhav Jain (LBL)
Date: 2/6/2015 Time: 10:30 AM - 11:30 AM
Abstract: It has now been demonstrated that density functional theory (DFT) calculations can be used to design new materials in several technological areas from first principles. This talk will cover two main efforts: (i) the application DFT calculations towards the design of new materials for next-generation Li ion and multivalent ion batteries and (ii) the Materials Project, an open public database of computed materials properties that includes over 60,000 materials entries and represents over 40 million CPU-hours of computation at the NERSC supercomputing center.
The first part of this talk will concentrate on our high-throughput efforts to discover new cathode materials for Li ion batteries, including a description of over 20,000 materials screened computationally, experimental "hits", and new statistical rules regarding battery design. I will also talk about recent efforts in the multivalent aren, in which cations like Mg2+ and Ca2+ are used instead of Li to transfer additional charge and potentially make possible the use of energy dense metal anodes.
The second part of this talk will focus on the Materials Project (MP), a multi-institution effort to compute the fundamental properties of all known inorganic materials and beyond. Currently, the MP web site has registered almost 10,000 users (including ~15% from industry) and includes data on over 60,000 compounds. This dataset also includes almost 30,000 band structures and over 1000 full elastic tensors (to our knowledge, the largest such data set). I will discuss the fundamental software infrastructure that makes this effort possible as well as real use cases by the community. Finally, I will discuss upcoming developments such as user data contribution and the possibility to suggest new compounds for computation.
Topic: Towards Computational Design of the Optoelectronic Properties of Organic Semiconductors
Speaker: Sahar Sharifzadeh (Boston University)
Date: 4/24/2015 Time: 10:30 AM - 11:30 AM
Location: Auditorium A
Abstract: Organic semiconductors are a highly tunable class of optically active materials that are promising as next-generation photovoltaics. Design of these materials for efficient solar energy conversion relies on building physical intuition that connects chemistry and solid-state morphology to their functional properties. Here, I will present recent computational studies, based on first-principles many-body perturbation theory, aimed at understanding the spectroscopic properties of select organic crystalline semiconductors, and improving these properties for enhanced photovoltaic performance. For both gas-phase molecules and condensed-phase crystals, our quantitative calculations agree well with transport gaps extracted from photoemission spectroscopy and conductance measurements, as well as with measured polarization-dependent optical absorption spectra. Introducing a new analysis of the electron-hole correlation function, we elucidate the nature of low‐lying solid-state singlet and triplet optical excitations (excitons). We demonstrate significant exciton binding energies and charge-transfer character in these systems, providing new insight into the complexities of excitonic effects within organic crystals. Collectively, this work reveals new ways in which the nature of the exciton can be controlled through solid-state morphology or change of conjugation length, enabling the deliberate design of novel functional organic materials.
Topic: Resonant Soft X-ray Scattering for Soft Materials
Speaker: Cheng Wang (LBNL)
Date: 5/15/2015 Time: 10:30 AM - 11:30 AM
Location: Auditorium A
Abstract: To meet the challenge of investigating new and complex materials that is relevant to mesoscale energy science, it is essential to connect microscopic dynamical processes to activated kinetic processes and macroscopic function in diverse soft and hard materials. We need sharper tools in order to discover, understand, and control mesoscale phenomena and architectures. Over the past a few years, we have developed Resonant Soft X-ray Scattering (RSoXS) and constructed the first dedicated resonant soft x-ray scattering beamline at the Advanced Light Source, LBNL. RSoXS combines soft x-ray spectroscopy with x-ray scattering thus offers statistical information for 3D chemical morphology over a large length scale range from nanometers to micrometers. Using RSoXS to characterize multi-length scale soft materials with heterogenous chemical structures, we have demonstrated that soft x-ray scattering is a unique complementary technique to conventional hard x-ray and neutron scattering. Its unique chemical sensitivity, large accessible size scale, molecular bond orientation sensitivity with polarized x-rays and high coherence have shown great potential for chemical/morphological structure characterization for many classes of materials. Some recent development of in-situ soft x-ray scattering with in-vacuum sample environment will be discussed. In order to study sciences in naturally occurring conditions, we need to overcome the sample limitations set by the low penetration depth of soft x-rays and requirement of high vacuum. Adapting to the evolving environmental cell designs utilized increasingly in the Electron Microscopy community, customized designed liquid/gas environmental cells will enable soft x-ray scattering experiments on biological, electro-chemical, self-assembly, and hierarchical functional systems in both static and dynamic fashion. Recent RSoXS results on organic electronics, block copolymer thin films, and membrane structure will be presented.