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Dynamics of Quantum Fluids: Path integral and Semiclassical Methods
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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...
Computational Nanoscience, Lecture 20: Quantum Monte Carlo, part I
15 May 2008 | | Contributor(s):: Elif Ertekin, Jeffrey C Grossman
This lecture provides and introduction to Quantum Monte Carlo methods. We review the concept of electron correlation and introduce Variational Monte Carlo methods as an approach to going beyond the mean field approximation. We describe briefly the Slater-Jastrow expansion of the wavefunction,...
Computational Nanoscience, Lecture 21: Quantum Monte Carlo, part II
15 May 2008 | | Contributor(s):: Jeffrey C Grossman, Elif Ertekin
This is our second lecture in a series on Quantum Monte Carlo methods. We describe the Diffusion Monte Carlo approach here, in which the approximation to the solution is not restricted by choice of a functional form for the wavefunction. The DMC approach is explained, and the fixed node...
Computational Nanoscience, Pop-Quiz
This quiz summarizes the most important concepts which have covered in class so far related to Molecular Dynamics, Classical Monte Carlo Methods, and Quantum Mechanical Methods.University of California, Berkeley
Computational Nanoscience, Pop-Quiz Solutions
The solutions to the pop-quiz are given in this handout.University of California, Berkeley
UV/Vis Spectra simulator
04 Mar 2008 | | Contributor(s):: Baudilio Tejerina
This tool computes molecular electronic spectra.
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...
09 Oct 2007 | | Contributor(s):: Baudilio Tejerina, Jeff Reimers
Semi-empirical Molecular Orbital calculations.
Computational Nanoscience, Lecture 4: Geometry Optimization and Seeing What You're Doing
13 Feb 2008 | | Contributor(s):: Jeffrey C Grossman, Elif Ertekin
In this lecture, we discuss various methods for finding the ground state structure of a given system by minimizing its energy. Derivative and non-derivative methods are discussed, as well as the importance of the starting guess and how to find or generate good initial structures. We also briefly...
Exploring Physical and Chemical control of molecular conductance: A computational study
31 Jan 2008 | | 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 | | 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...
MIT Atomic-Scale Modeling Toolkit
15 Jan 2008 | | Contributor(s):: daniel richards, Elif Ertekin, Jeffrey C Grossman, David Strubbe, Justin Riley
Tools for Atomic-Scale Modeling
Perspectives on Computational Quantum Chemistry
20 Dec 2007 | | Contributor(s):: Martin P. Head-Gordon
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.
Computational Mathematics: Role, Impact, Challenges
20 Dec 2007 | | Contributor(s):: Juan C. Meza
Excellence in Computer Simulation
19 Dec 2007 | | Contributor(s):: Mark Lundstrom, Jeffrey B. Neaton, Jeffrey C Grossman
Computational science is frequently labeled as a third branch of science - equal in standing with theory and experiment, and computational engineering is now an essential component of technology development and manufacturing. The successes of computational science and engineering (CSE) over the...
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...
The basics of quantum Monte Carlo
15 Jun 2007 | | Contributor(s):: Lucas Wagner, Jeffrey C Grossman, Jeffrey B. Neaton
Quantum Monte Carlo is a highly accurate method to approximately solve the Schrodinger equation. I explain quantum Monte Carlo in a way that should be accessible to someone who is somewhat familiar with quantum mechanics. The discussion is mostly conceptual.Lucas Wagner is a postdoctoral...
Finite Size Scaling and Quantum Criticality
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...
Molecular Workbench: An Interface to the Molecular World
25 Jun 2006 | | Contributor(s):: Charles Xie
The Molecular Workbench software is a free, open-source modeling and authoring program specifically designed for use in science education. Powered by a set of real-time molecular simulation engines that compute and visualize the motion of particles interacting through force fields, in both 2D...