Designer Atoms: Engineering Rydberg Atoms Using Pulsed Electric Fields
20 Jun 2008 | Online Presentations | Contributor(s): F. Barry Dunning
Advances in experimental technique allow application of pulsed unidirectional electric fields, termed half-cycle pulses (HCPs), to Rydberg atoms whose characteristic times are much less than the classical electron orbital period. In this limit each HCP simply delivers an impulsive momentum transfer, or "kick", to the excited electron. A number of protocols for controlling and manipulating Rydberg atom wavepackets using carefully-tailored sequences of HCPs will be described with emphasis on the ...
Dynamics of Quantum Fluids: Path integral and Semiclassical Methods
21 May 2008 | Online Presentations | Contributor(s): Nancy Makri
The interplay of many-body nonlinear interactions and quantum mechanical effects such as zero-point motion or identical particle exchange symmetries lead to intriguing phenomena in low-temperature fluids, some of which remain poorly understood. Recent advances in theory and methodology have established the framework that has recently enabled the simulation of time-dependent processes in such systems. This lecture focuses on the development of path integral and semiclassical methods and their application to the dynamics of quantum fluids.
Calculating Resonances Using a Complex Absorbing Potential
13 Mar 2008 | Online Presentations | Contributor(s): Robin Santra
The Siegert (or Gamow) wave function associated with a resonance state is exponentially divergent at large distances from the scattering target. A complex absorbing potential (CAP) provides a computationally simple and efficient technique for calculating the complex Siegert energy of a resonance within a square-integrable basis. Some aspects of the associated complex symmetric eigenvalue problem will be addressed. Applications to the decay of inner-shell holes, to elastic electron-molecule scattering, and to multiphoton processes will be described.
Exploring Physical and Chemical control of molecular conductance: A computational study
31 Jan 2008 | Online Presentations | Contributor(s): Barry D. Dunietz
Dynamics on the Nanoscale: Time-domain ab initio studies of quantum dots, carbon nanotubes and molecule-semiconductor interfaces
31 Jan 2008 | Online Presentations | Contributor(s): Oleg Prezhdo
Device miniaturization requires an understanding of the dynamical response of materials on the nanometer scale. A great deal of experimental and theoretical work has been devoted to characterizing the excitation, charge, spin, and vibrational dynamics in a variety of novel materials, including carbon nanotubes, quantum dots, conducting polymers, inorganic semiconductors and molecular chromophores. We have developed state-of-the-art non-adiabatic molecular dynamics techniques and implemented ...