Results 261 to 270 of about 205,731 (305)

Renormalized finite-cluster expansions

Physical Review B, 1987
There are many statistical systems in which degrees of freedom can be grouped according to their degree of correlation. We develop a cluster-expansion method for these systems based on selecting finite clusters of the most strongly interacting degrees of freedom. The starting point is Kubo's generalized cumulant formalism.
, Singer, , Weeks
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The Cluster Expansion

1981
The cluster expansion [Glimm, Jaffe and Spencer, 1973, 1974] allows a detailed study of the properties of quantum fields. Consequences of the cluster expansion, in addition to the proof of existence of the infinite volume limit, are the detailed properties of the spectrum: the multiplicity of the ground state, the existence of isolated particle ...
James Glimm, Arthur Jaffe
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The Cluster Expansion

1999
The central topic of this chapter is the derivation of diagrammatic perturbation theory, which lays the basis for all the subsequent analysis.
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Cluster-expansion representation

Journal of Physics A: Mathematical and General, 1996
Summary: We describe how starting from a type of nearest-neighbour localized wavefunction cluster expansion one may conveniently build up a locally correlated orthonormal `many-body' basis for a linear-chain system. The initial correlated cluster expansion approximant to the ground state plays the role of a `vacuum' while the other members of the basis
Garcia-Bach, M. A., Klein, D. J.
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Clustering Based on Dominant Set and Cluster Expansion

2017
While numerous clustering algorithms can be found in the literature, existing algorithms are usually afflicted by two major problems. First, the majority of clustering algorithms requires user-specified parameters as input, and their clustering results rely heavily on these parameters. Second, many algorithms generate clusters of only spherical shapes.
Jian Hou 0001, Wei-Xue Liu
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Generalized cluster expansions

Journal of Low Temperature Physics, 1969
A unified approach to the cluster expansion of the ground-state energy of a system whose wave function is a product of two factors, one of which is a Jastrow function, is presented. It is shown that several previously derived expansions, notably those of Wu and Feenberg and of Massey and Woo, are special cases of this one. The most general case of this
R. D. Murphy, L. H. Nosanow
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Dynamical Expansion of Star Clusters

2011
Most globular clusters have half-mass radii of a few pc with no apparent correlation with their masses. This is different from elliptical galaxies, for which the Faber-Jackson relation suggests a strong positive correlation between mass and radius. Objects that are somewhat in between globular clusters and low-mass galaxies, such as ultra-compact dwarf
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Cluster expansion of the wavefunction

Theoretica Chimica Acta, 1987
Numerical examples illustrate the SAC and SAC-CI results for correlatioin energies compared to those from full CI calculations of Bauschlicher and Taylor.
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Pseudo-cluster expansion

Nuclear Physics, 1960
Abstract The Ursell-Mayer cluster expansion method is extended to the case of a q-number model operator for either boson or fermion systems. The many-body problem for a system with strong, hard sphere interactions can be approximately reduced to that for a weakly interacting system without hard sphere interactions.
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Category Expansion by Clustering in Webpage Classification

2007
Automatic classification of web pages is an effective way to facilitate the process of retrieving information from the Internet. But most of the algorithms that have been published ignore the conflict between the fixed number of categories and the growing number of documents being added to the system.
Xiaogang Peng, Zhen Ji, Xianghua Fu
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