16,327 research outputs found
QCDGPU: open-source package for Monte Carlo lattice simulations on OpenCL-compatible multi-GPU systems
The multi-GPU open-source package QCDGPU for lattice Monte Carlo simulations
of pure SU(N) gluodynamics in external magnetic field at finite temperature and
O(N) model is developed. The code is implemented in OpenCL, tested on AMD and
NVIDIA GPUs, AMD and Intel CPUs and may run on other OpenCL-compatible devices.
The package contains minimal external library dependencies and is OS
platform-independent. It is optimized for heterogeneous computing due to the
possibility of dividing the lattice into non-equivalent parts to hide the
difference in performances of the devices used. QCDGPU has client-server part
for distributed simulations. The package is designed to produce lattice gauge
configurations as well as to analyze previously generated ones. QCDGPU may be
executed in fault-tolerant mode. Monte Carlo procedure core is based on PRNGCL
library for pseudo-random numbers generation on OpenCL-compatible devices,
which contains several most popular pseudo-random number generators.Comment: Presented at the Third International Conference "High Performance
Computing" (HPC-UA 2013), Kyiv, Ukraine; 9 pages, 2 figure
Asymptotic Scaling and Infrared Behavior of the Gluon Propagator
The Landau gauge gluon propagator for the pure gauge theory is evaluated on a
32^3x64 lattice with a physical volume of (3.35^3x6.7)fm^4. Comparison with two
smaller lattices at different lattice spacings allows an assessment of finite
volume and finite lattice spacing errors. Cuts on the data are imposed to
minimize these errors. Scaling of the gluon propagator is verified between
beta=6.0 and beta=6.2. The tensor structure is evaluated and found to be in
good agreement with the Landau gauge form, except at very small momentum
values, where some small finite volume errors persist. A number of functional
forms for the momentum dependence of the propagator are investigated. The form
D(q^2)=D_ir+D_uv, where D_ir(q^2) ~ (q^2+M^2)^-\eta and D_uv is an infrared
regulated one-loop asymptotic form, is found to provide an adequate description
of the data over the entire momentum region studied - thereby bridging the gap
between the infrared confinement region and the ultraviolet asymptotic region.
The best estimate for the exponent \eta is 3.2(+0.1/-0.2)(+0.2/-0.3), where the
first set of errors represents the uncertainty associated with varying the
fitting range, while the second set of errors reflects the variation arising
from different choices of infrared regulator in D_uv. Fixing the form of D_uv,
we find that the mass parameter M is (1020+/-100)MeV.Comment: 37 pages, RevTeX, 16 postscript figures, 7 gif figures. Revised
version accepted for publication in Phys. Rev. D. Model functions and
discussion of asymptotic behaviour modified; all model fits have been redone.
This paper, including postscript version of all figures, can be found at
http://www.physics.adelaide.edu.au/~jskuller/papers
Experimental evidence of percolation phase transition in surface plasmons generation
Carrying digital information in traditional copper wires is becoming a major
issue in electronic circuits. Optical connections such as fiber optics offers
unprecedented transfer capacity, but the mismatch between the optical
wavelength and the transistors size drastically reduces the coupling
efficiency. By merging the abilities of photonics and electronics, surface
plasmon photonics, or 'plasmonics' exhibits strong potential. Here, we propose
an original approach to fully understand the nature of surface electrons in
plasmonic systems, by experimentally demonstrating that surface plasmons can be
modeled as a phase of surface waves. First and second order phase transitions,
associated with percolation transitions, have been experimentally observed in
the building process of surface plasmons in lattice of subwavelength apertures.
Percolation theory provides a unified framework for surface plasmons
description
SUE: A Special Purpose Computer for Spin Glass Models
The use of last generation Programmable Electronic Components makes possible
the construction of very powerful and competitive special purpose computers. We
have designed, constructed and tested a three-dimensional Spin Glass model
dedicated machine, which consists of 12 identical boards. Each single board can
simulate 8 different systems, updating all the systems at every clock cycle.
The update speed of the whole machine is 217ps/spin with 48 MHz clock
frequency. A device devoted to fast random number generation has been developed
and included in every board. The on-board reprogrammability permits us to
change easily the lattice size, or even the update algorithm or the action. We
present here a detailed description of the machine and the first runs using the
Heat Bath algorithm.Comment: Submitted to Computer Physics Communications, 19 pages, 5 figures,
references adde
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