Final Report: Biological and Synthetic Nanostructures Controlled at the Atomistic Level

Nanotechnology holds great promise for many application fields, ranging from the semiconductor industry to medical research and national security. Novel, nanostructured materials are the fundamental building blocks upon which all these future nanotechnologies will be based. In this Strategic Initiative (SI) we conducted a combined theoretical and experimental investigation of the modeling, synthesis, characterization, and design techniques which are required to fabricate semiconducting and metallic nanostructures with enhanced properties. We focused on developing capabilities that have broad applicability to a wide range of materials and can be applied both to nanomaterials that are currently being developed for nanotechnology applications and also to new, yet to be discovered, nanomaterials. During this 3 year SI project we have made excellent scientific progress in each of the components of this project. We have developed first-principles techniques for modeling the structural, electronic, optical, and transport properties of materials at the nanoscale. For the first time, we have simulated nanomaterials both in vacuum and in aqueous solution. These simulation capabilities harness the worldleading computational resources available at LLNL to model, at the quantum mechanical level, systems containing hundreds of atoms and thousands of electrons. Significant advances in the density functional and quantum Monte Carlo techniques employed in this project were developed to enable these techniques to scale up to simulating realistic size nanostructured materials. We have developed the first successful techniques for chemically synthesizing crystalline silicon and germanium nanoparticles and nanowires. We grew the first macroscopic, faceted superlattice crystals from these nanoparticles. We have also advanced our capabilities to synthesize semiconductor nanoparticles using physical vapor deposition techniques so that we are now able to control of the size, shape and surface structure of these nanoparticles. We have made advances in characterizing the surface of nanoparticles using x-ray absorption experiments. Throughout this SI a number of long-term, strategic external collaborations have been established. These collaborations have resulted in 30 joint publications, strategic hires of postdocs and graduate students from these groups into groups at LLNL and the submission of joint research grants. We have developed collaborations on the theory and modeling of nanomaterials with the groups of Profs. Ceder and Marzari (MIT), Crespi (Penn State), Freeman (Northwestern), Grossman and Lester (UC Berkeley), Mitas (North Carolina State), and Needs (Cambridge). We are collaborating with Dr. Alivisatos's group in the Molecular Foundry at Lawrence Berkeley Laboratory on the fabrication, characterization and modeling of inorganic nanomaterials. We are working with Prof. Majumdar's group at UC Berkeley on the characterization of nanomaterials. We are working with the molecular diamond group at Chevron-Texaco who has developed a process for extracting mono-disperse samples of nano-scale diamonds from crude oil. We are collaborating with Dr. Chen at UCSF to develop CdSe nanoparticle-biolabels. As a result of the outstanding scientific achievements and the long-term collaborations developed during this strategic initiative we have been extremely successful in obtaining external funding to continue and grow this research activity at the LLNL. We have received two DARPA grants to support the further development of our computational modeling techniques and to develop carbon nanotube based molecular separation devices. We have received two new Office of Science BES grants to support our nanomaterials modeling and synthesis projects. We have received funding from the NA22 office of DOE to develop the materials modeling capabilities begun in this SI for modeling detector materials. We have received funding from Intel Corporation to apply the modeling techniques developed in this initiative to examine silicon nanowires fabricated on computer chips. We are also pursuing several additional sources of funding from BES, the DHS, and NIH to support the continuation of the research programs developed in this SI. The remainder of this report and the attached publications describe the background to this SI research project and the details of the scientific achievements that have been made