3,013 research outputs found
Inter-dimensional Degeneracies in van der Waals Clusters and Quantum Monte Carlo Computation of Rovibrational States
Quantum Monte Carlo estimates of the spectrum of rotationally invariant
states of noble gas clusters suggest inter-dimensional degeneracy in and
spacial dimensions. We derive this property by mapping the Schr\"odinger
eigenvalue problem onto an eigenvalue equation in which appears as a
continuous variable. We discuss implications for quantum Monte Carlo and
dimensional scaling methods
Van der Waals clusters in the ultra-quantum limit: a Monte Carlo study
Bosonic van der Waals clusters of sizes three, four and five are studied by
diffusion quantum Monte-Carlo techniques. In particular we study the unbinding
transition, the ultra-quantum limit where the ground state ceases to exist as a
bound state. We discuss the quality of trial wave functions used in the
calculations, the critical behavior in the vicinity of the unbinding
transition, and simple improvements of the diffusion Monte Carlo algorithm.Comment: World Wide Web URL
http://www.phys.uri.edu/people/mark_meierovich/visual/Main.html contains an
informal presentation with color graphic
Surface and bulk transitions in three-dimensional O(n) models
Using Monte Carlo methods and finite-size scaling, we investigate surface
criticality in the O models on the simple-cubic lattice with , 2, and
3, i.e. the Ising, XY, and Heisenberg models. For the critical couplings we
find and . We
simulate the three models with open surfaces and determine the surface magnetic
exponents at the ordinary transition to be ,
, and for , 2, and 3, respectively. Then we vary
the surface coupling and locate the so-called special transition at
and , where
. The corresponding surface thermal and magnetic exponents are
and for the Ising
model, and and for
the XY model. Finite-size corrections with an exponent close to -1/2 occur for
both models. Also for the Heisenberg model we find substantial evidence for the
existence of a special surface transition.Comment: TeX paper and 10 eps figure
Automotive Stirling Engine Development Program
Activities performed on Mod I engine testing and test results; the manufacture, assembly, and test of a Mod I engine in the United States; design initiation of the Mod I-A engine system; transient performance testing; Stirling reference engine manufacturing and reduced size studies; components and subsystems; and the study and test of low cost alloys are summarized
Transfer-matrix approach to the three-dimensional bond percolation: An application of Novotny's formalism
A transfer-matrix simulation scheme for the three-dimensional (d=3) bond
percolation is presented. Our scheme is based on Novotny's transfer-matrix
formalism, which enables us to consider arbitrary (integral) number of sites N
constituting a unit of the transfer-matrix slice even for d=3. Such an
arbitrariness allows us to perform systematic finite-size-scaling analysis of
the criticality at the percolation threshold. Diagonalizing the transfer matrix
for N =4,5,...,10, we obtain an estimate for the correlation-length critical
exponent nu = 0.81(5)
Finite size scaling of the correlation length above the upper critical dimension
We show numerically that correlation length at the critical point in the
five-dimensional Ising model varies with system size L as L^{5/4}, rather than
proportional to L as in standard finite size scaling (FSS) theory. Our results
confirm a hypothesis that FSS expressions in dimension d greater than the upper
critical dimension of 4 should have L replaced by L^{d/4} for cubic samples
with periodic boundary conditions. We also investigate numerically the
logarithmic corrections to FSS in d = 4.Comment: 5 pages, 6 postscript figure
Automotive Stirling Engine Development Program
Mod I engine testing and test results, the test of a Mod I engine in the United States, Mod I engine characterization and analysis, Mod I Transient Test Bed fuel economy, Mod I-A engine performance are discussed. Stirling engine reference engine manufacturing and reduced size studies, components and subsystems, and the study and test of low-cost casting alloys are also covered. The overall program philosophy is outlined, and data and results are presented
Critical Excitation Spectrum of Quantum Chain With A Local 3-Spin Coupling
This article reports a measurement of the low-energy excitation spectrum
along the critical line for a quantum spin chain having a local interaction
between three Ising spins and longitudinal and transverse magnetic fields. The
measured excitation spectrum agrees with that predicted by the (D, A)
conformal minimal model under a nontrivial correspondence between translations
at the critical line and discrete lattice translations. Under this
correspondence, the measurements confirm a prediction that the critical line of
this quantum spin chain and the critical point of the 2D 3-state Potts model
are in the same universality class.Comment: 7 pages, 2 figure
Automotive Stirling Engine Development Program
Program status and plans are discussed for component and technology development; reference engine system design, the upgraded Mod 1 engine; industry test and evaluation; and product assurance. Four current Mod 1 engines reached a total of 2523 operational hours, while two upgraded engines accumulated 166 hours
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