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"Ab Initio" Theory of Novel Micro and Nanolasers
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19 May 2008 | | Contributor(s):: A. Douglas Stone
While the laser is one of the most important inventions of the past century and one of the most interesting and controllable non-linear systems in physics, there is surprisingly little predictive theory of lasing properties. Predicting lasing thresholds and output power far above threshold in...
BNC Annual Research Review: An Introduction to PRISM and MEMS Simulation
04 Jun 2008 | | Contributor(s):: Jayathi Murthy
This presentation is part of a collection of presentations describing the projects, people, and capabilities enhanced by research performed in the Birck Center, and a look at plans for the upcoming year.
Calculating Resonances Using a Complex Absorbing Potential
13 Mar 2008 | | 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...
Computational Mathematics: Role, Impact, Challenges
20 Dec 2007 | | Contributor(s):: Juan C. Meza
This presentation was one of 13 presentations in the one-day forum, "Excellence in Computer Simulation," which brought together a broad set of experts to reflect on the future of computational science and engineering.
Dynamics of Quantum Fluids: Path integral and Semiclassical Methods
21 May 2008 | | 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...
Dynamics on the Nanoscale: Time-domain ab initio studies of quantum dots, carbon nanotubes and molecule-semiconductor interfaces
31 Jan 2008 | | 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...
Excellence in Computer Simulation: Computational Materials
20 Dec 2007 | | Contributor(s):: Eric Schwegler
Exploring Physical and Chemical control of molecular conductance: A computational study
31 Jan 2008 | | Contributor(s):: Barry D. Dunietz
Finite Size Scaling and Quantum Criticality
02 Jan 2008 | | Contributor(s):: Sabre Kais
In statistical mechanics, the finite size scaling method provides a systematic way to extrapolate information about criticality obtained from a finite system to the thermodynamic limit. For quantum systems, the finite size corresponds not to the spatial dimension but to the number of elements in...
09 May 2007 | | Contributor(s):: Sabre Kais
The study of quantum phase transitions, which are driven by quantum fluctuations as a consequence of Heisenberg's uncertainty principle, continues to be of increasing interest in the fields of condensed matter and atomic and molecular physics. In this field we have established an analogy between...
IMA 2013 UQ: DFT-based Thermal Properties: Three Levels of Error Management
02 Apr 2014 | | Contributor(s):: Kurt Lejaeghere
It is often computationally expensive to predict finite-temperature properties of a crystal from density-functional theory (DFT). The temperature-dependent thermal expansion coefficient α, for example, is calculated from the phonon spectrum, and the melting temperature Tm can only be obtained...
Lecture 4: The ab-initio Wigner Monte Carlo Method
18 Nov 2014 | | Contributor(s):: Jean Michel D Sellier
In this lecture, Dr. Sellier discusses the ab-initio Wigner Monte Carlo method for the simulation of strongly correlated systems.
MCW07 Electronic Level Alignment at Metal-Molecule Contacts with a GW Approach
05 Sep 2007 | | Contributor(s):: Jeffrey B. Neaton
Most recent theoretical studies of electron transport in single-molecule junctions rely on a Landauer approach, simplified to treat electron-electron interactions at a mean-field level within density functional theory (DFT). While this framework has proven relatively accurate for certain...
MCW07 Modeling Charging-based Switching in Molecular Transport Junctions
23 Aug 2007 | | Contributor(s):: Sina Yeganeh, , Mark Ratner
We will discuss several proposed explanations for the switching and negative differential resistance behavior seen in some molecular junctions. It is shown that a proposed polaron model is successful in predicting both hysteresis and NDR behavior, and the model is elaborated with image charge...
MSE 597G Lecture 6: Interatomic potentials III
12 Nov 2008 | | Contributor(s):: Alejandro Strachan
Reactive force fields,Parameterization of interatomic potentials
OPV: Large Scale Ab Initio Simulation for Charge Transport in Disordered Organic Systems
31 Jan 2011 | | Contributor(s):: Lin-Wang Wang
This presentation was part of the "Organic Photovoltaics: Experiment and Theory" workshop at the 2010 Users' Meeting of the Molecular Foundry and the National Center for Electron Microscopy, both DOE-funded Research Centers at Lawrence Berkeley National Laboratory.
OPV: Time Domain Ab Initio Studies of Organic-Inorganic Composites for Solar Cells
31 Jan 2011 | | Contributor(s):: Oleg Prezhdo
Perspectives on Computational Quantum Chemistry
20 Dec 2007 | | Contributor(s):: Martin P. Head-Gordon
Renormalization Group Theories of Strongly Interacting Electronic Structure
20 Apr 2007 | | Contributor(s):: Garnet Chan, NCN at Northwestern University
Our work is in the area of the electronic structure and dynamics of complex processes. We engage in developing new and more powerful theoretical techniques which enable us to describe strong electronic correlation problems.Of particular theoretical interest are the construction of fast...
Ripples and Warping of Graphene: A Theoretical Study
19 May 2010 | | Contributor(s):: Umesh V. Waghmare
We use first-principles density functional theory based analysis to understand formation of ripples in graphene and related 2-D materials. For an infinite graphene, we show that ripples are linked with a low energy branch of phonons that exhibits quadratic dispersion at long wave-lengths. Many...