A coordinate-space study of kowalski's three-term separable approximation for the fully off-shell two-nucleon T-matrix

1975 ◽  
Vol 241 (3) ◽  
pp. 443-459 ◽  
Author(s):  
H.S. Picker ◽  
G.J. Stephenson
Keyword(s):  
Coordinate Space ◽  
Separable Approximation ◽  
T Matrix

Liquid helium and the properties of a Bose–Einstein gas. III. The density dependence of hard-core models

1970 ◽  
Vol 48 (11) ◽  
pp. 1340-1364
Author(s):  
D. F. Goble
Keyword(s):  
Density Dependence ◽  
Liquid Helium ◽  
Hard Core ◽  
Ladder Approximation ◽  
Model Systems ◽  
Coordinate Space ◽  
Core Boundary ◽  
T Matrix ◽  
Bose Einstein ◽  
Space Method

We have used the results of a previous paper by Goble and Trainor to compute the density dependence of the hard-core Bose–Einstein gas in the t-matrix ladder approximation, utilizing the coordinate-space method of Brueckner and Sawada as modified by Parry and ter Haar, and the pseudopotential treatment of the hard-core boundary condition presented by Liu and Wong. Various thermodynamic parameters of these model systems are compared with the properties of liquid helium four. The disagreements which are found are shown to be primarily related to differences in the magnitudes of the Landau parameters.

A separable approximation to the two-body t-matrix for short-range central local potentials

1971 ◽  
Vol 167 (2) ◽  
pp. 376-382 ◽  
Author(s):  
Gita Purkayastha ◽  
S.N. Banerjee ◽  
N.C. Sil
Keyword(s):  
Short Range ◽  
Separable Approximation ◽  
Local Potentials ◽  
T Matrix

T-Matrix Simulation of Plasmon Resonances of Particles on or near a Surface

PIERS Online ◽  
2006 ◽  
Vol 2 (5) ◽  
pp. 450-454
Author(s):  
Norbert Riefler ◽  
Thomas Wriedt
Keyword(s):  
Plasmon Resonances ◽  
T Matrix

Systems with Condensates and Pairing

2018 ◽  
Author(s):  
Klaus Morawetz
Keyword(s):  
Critical Parameters ◽  
Einstein Condensation ◽  
Cooper Pairs ◽  
Pair Breaking ◽  
Systematic Theory ◽  
Bose Einstein Condensation ◽  
T Matrix ◽  
The Stability ◽  
Bose Einstein

The Bose–Einstein condensation and appearance of superfluidity and superconductivity are introduced from basic phenomena. A systematic theory based on the asymmetric expansion of chapter 11 is shown to correct the T-matrix from unphysical multiple-scattering events. The resulting generalised Soven scheme provides the Beliaev equations for Boson’s and the Nambu–Gorkov equations for fermions without the usage of anomalous and non-conserving propagators. This systematic theory allows calculating the fluctuations above and below the critical parameters. Gap equations and Bogoliubov–DeGennes equations are derived from this theory. Interacting Bose systems with finite temperatures are discussed with successively better approximations ranging from Bogoliubov and Popov up to corrected T-matrices. For superconductivity, the asymmetric theory leading to the corrected T-matrix allows for establishing the stability of the condensate and decides correctly about the pair-breaking mechanisms in contrast to conventional approaches. The relation between the correlated density from nonlocal kinetic theory and the density of Cooper pairs is shown.

scholarly journals Standardizing human brain parcellations

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ross M. Lawrence ◽  
Eric W. Bridgeford ◽  
Patrick E. Myers ◽  
Ganesh C. Arvapalli ◽  
Sandhya C. Ramachandran ◽  
...  
Keyword(s):  
Human Brain ◽  
Coordinate Space ◽  
The Past ◽  
File Storage ◽  
Statistical Inferences ◽  
Standardized Protocol ◽  
Storage Format ◽  
Labeling Scheme ◽  
Selection Of ◽  
Brain Atlases

AbstractUsing brain atlases to localize regions of interest is a requirement for making neuroscientifically valid statistical inferences. These atlases, represented in volumetric or surface coordinate spaces, can describe brain topology from a variety of perspectives. Although many human brain atlases have circulated the field over the past fifty years, limited effort has been devoted to their standardization. Standardization can facilitate consistency and transparency with respect to orientation, resolution, labeling scheme, file storage format, and coordinate space designation. Our group has worked to consolidate an extensive selection of popular human brain atlases into a single, curated, open-source library, where they are stored following a standardized protocol with accompanying metadata, which can serve as the basis for future atlases. The repository containing the atlases, the specification, as well as relevant transformation functions is available in the neuroparc OSF registered repository or https://github.com/neurodata/neuroparc.

scholarly journals Tensor-structured algorithm for reduced-order scaling large-scale Kohn–Sham density functional theory calculations

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Chih-Chuen Lin ◽  
Phani Motamarri ◽  
Vikram Gavini
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Density Functional Theory Calculations ◽  
System Size ◽  
Real Space ◽  
Functional Theory ◽  
Reduced Order ◽  
Separable Approximation ◽  
Tensor Basis

AbstractWe present a tensor-structured algorithm for efficient large-scale density functional theory (DFT) calculations by constructing a Tucker tensor basis that is adapted to the Kohn–Sham Hamiltonian and localized in real-space. The proposed approach uses an additive separable approximation to the Kohn–Sham Hamiltonian and an L1 localization technique to generate the 1-D localized functions that constitute the Tucker tensor basis. Numerical results show that the resulting Tucker tensor basis exhibits exponential convergence in the ground-state energy with increasing Tucker rank. Further, the proposed tensor-structured algorithm demonstrated sub-quadratic scaling with system-size for both systems with and without a gap, and involving many thousands of atoms. This reduced-order scaling has also resulted in the proposed approach outperforming plane-wave DFT implementation for systems beyond 2000 electrons.

scholarly journals THEORY OF COMPLEX SCATTERING LENGTHS

2001 ◽  
Vol 15 (03) ◽  
pp. 105-109
Author(s):  
M. S. HUSSEIN
Keyword(s):  
Scattering Length ◽  
Effective Range ◽  
Low Energies ◽  
T Matrix ◽  
Scattering Lengths ◽  
New Equation ◽  
Molecule Interaction ◽  
Complex Atom

We derive a generalized Low equation for the T-matrix appropriate for complex atom–molecule interaction. The properties of this new equation at very low energies are studied and the complex scattering length and effective range are derived.

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