Special events.

Dynamics of organization at the nanometer scale: Self-assembly of protein arrays and nanocrystal superstructures

The practice of small molecule chemistry could be viewed as a mastery of self-organization at the atomic scale. Recent advances in nanomaterial synthesis has inspired attempts to replicate that feat with building blocks that are considerably larger, though still microscopic. Limited success in this endeavor reflects a host of new challenges, many of them dynamical in nature. We have explored the statistical dynamics of nanoparticle self-assembly in the context of two model systems, comprising chaperonin protein complexes in one case and magnetic nanocrystals in another.

Quantum wavepacket ab initio molecular dynamics: Applications to Hydrogen Tunneling in Biological Enzymes and Vibrational Properties in Hydrogen-Bonded Clusters

Abstract: This talk is arranged in three parts: The first part of the talk deals with the discussion of a novel computational methodology developed within our group. The approach combines quantum wavepacket dynamics with ab initio molecular dynamics and is potentially useful in studying problems where nuclear quantum effects can play a significant role. Computational bottlenecks and associated solutions are also discussed.

Band Alignment and Tunneling Conductance through Long Molecular Wires

Experiments indicate that the linear, low bias, conductance of devices made by long insulating molecular chains connected to metallic electrodes decays exponentially with the number n of monomers in the molecular chain, according to a simple tunneling law which depends on two parameters, the decay constant and the pre-exponential factor . Understanding how , the contact conductance, and depend on the properties of the molecule, of the electrodes, and of the contacts is an issue of relevant current interest.

Chemical Bonding in Astrophysical Environments: Simulations of Materials Under the High Pressures and Temperatures of Giant Planet Interiors and Other Extreme Conditions

We have studied covalently bonded materials under extreme pressures and temperatures relevant to the interiors of giant planets and other astrophysical bodies using a combination of ab initio Molecular Dynamics and novel simulations techniques. Recent results include the first quantum simulations of the ionic conductivity of water within Neptune and Uranus due to shock compression, and the rapid transformation of graphite to diamond through a meta-stable layered diamond intermediate.

Water Dynamics near Lipid Interfaces

Water layers in proximity of biological interfaces are strongly influenced by their properties due to specific water-surface interactions and the truncation of the hydrogen bond network. One of the efficient approaches to design a model system for such a system is to use reverse micelles - the nanosize water droplets surrounded by a monolayer of AOT amphiphilic surfactant. We investigate the dynamics of water in the reversed micelles of various sizes with two-dimensional infrared correlation spectroscopy in the OH stretching mode region.

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