Bulletin of the American Physical Society
2007 APS Four Corners Section/SPS Zone 16 Joint Fall Meeting
Volume 52, Number 14
Friday–Saturday, October 19–20, 2007; Flagstaff, Arizona
Session G2: Condensed Matter: Path Integrals |
Hide Abstracts |
Chair: Kris Andersen, Northern Arizona University Room: Chemistry (Bldg. 20) Room 225 |
Saturday, October 20, 2007 8:15AM - 8:51AM |
G2.00001: Path integral simulations for nanoelectronics Invited Speaker: As computer circuits shrink, devices are entering the nanoscale regime and quantum physics is becoming important. The biggest barrier to further decreases in size and increases in clock speed is excessive heat generation. Some physicists are proposing that many-body correlated quantum states of electrons may be exploited to make more energy efficient switches. In our research we are developing new simulation techniques to study highly correlated electron states in realistic device geometries and finite temperatures. The simulations are based on Feynman path integrals, which cast quantum statistical mechanics as a sum over worldlines, a mathematically equivalent alternative Schroedinger's differetial equation. Using Monte Carlo sampling on dozens to hundreds of electrons, we can simulate properties of an interacting electron fluid in a nanowire. Linear response theory relates fluctuations about equilibrium to conductivity. This gives us a new perspective on quantum phenomena, including quantized conductance steps and spin-charge separation. [Preview Abstract] |
Saturday, October 20, 2007 8:51AM - 9:03AM |
G2.00002: Path Integral Simulations of Graphene Hosam Yousif Some properties of graphene are explored using a path integral approach. The path integral method allows us to simulate relatively large systems using monte carlo techniques and extract thermodynamic quantities. We simulate the effects of screening a large external charge potential, as well as conductivity and charge distributions in graphene sheets. [Preview Abstract] |
Saturday, October 20, 2007 9:03AM - 9:15AM |
G2.00003: Path Integral Monte Carlo Study of the Electrical Polarizability of Dimerized Hydrogen Chains Mark Sanger, John Shumway Density functional theory is a powerful technique for obtaining ab initio properties of molecules. However, the commonly used techniques have well known weaknesses, especially when computing polarizabilites or band gaps. We have developed a new Quantum Monte Carlo(QMC) technique for calculating static polarizability of molecules using current-current correlation functions in imaginary-time path integrals. The method is applicable to isolated molecules as well as periodic structures. We present the successfull results obtained from simulating the polarizability of dimerized chains of hydrogen atoms at T=300K for both open and periodic boundary conditions. We find excellent agreement with high accuracy quantum chemistry estimates, with a very modest order($N^3$) scaling with system size and easy accommodation of periodic boundary conditions. [Preview Abstract] |
Saturday, October 20, 2007 9:15AM - 9:27AM |
G2.00004: Charging of Ge/Si Dots Sourabh Sinha, Sutharsan Ketharanathan, Jeff Drucker, John Shumway We have modeled the charging of Ge/Si dots with path integrals for comparison with C-V experiments. The experimental samples have small Ge huts or larger Ge-Si domes embedded~in n-doped Si. By applying a negative gate voltage and measuring capacitance, we can count the number of electrons that sit on the quantum dots. In our theoretical analysis, we model the system as thermal equilibrium between electrons bound to the dots and electrons in the bulk, doped Si. Since the electrons sit in quantized energy states on the dots, we model the thermodynamics with a Feynman path integral. The electrons feel an attractive potential from the strained Si and below the dot, which we have modeled with atomistic strain calculations and an effective mass model. Using Monte~Carlo sampling, we can directly sample the charge density for different temperatures, doping densities, and dot structures; allowing us to count the number of electrons on the dot and compare directly to experiments. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700