VARIATIONAL DESCRIPTION OF WEAKLY INTERACTING BOSE GASES IN 3 DIMENSIONS

2006 ◽  
Vol 20 (30n31) ◽  
pp. 5061-5070
Author(s):  
F. MAZZANTI ◽  
M. SAARELA ◽  
V. APAJA
Keyword(s):  
Structure Function ◽  
Excited States ◽  
Hard Spheres ◽  
Dynamic Properties ◽  
Dynamic Structure ◽  
Basis Functions ◽  
Three Dimensions ◽  
Bose Gases ◽  
Weakly Interacting ◽  
Good Agreement

Static and dynamic properties of a weakly interacting Bose gas of Hard Spheres in three dimensions are studied in the framework of the Correlated Basis Functions (CBF) approximation. Results are compared with explicit expressions for the same quantities derived within the Bogoliubov model. Despite the good agreement in the energy of the groundstate and the excited states, other quantities such as the dynamic structure function present important differences that become more significant when the density is raised.

scholarly journals Spin Waves in One Dimensional Magnetic Material

2015 ◽  
Vol 47 ◽  
pp. 24-39
Author(s):  
H.S. Wijesinhe ◽  
K.A.I.L. Wijewardena Gamalath
Keyword(s):  
Spin Wave ◽  
Numerical Solutions ◽  
Dynamic Properties ◽  
Equations Of Motion ◽  
Spin Waves ◽  
Dynamic Structure ◽  
Three Dimensions ◽  
Spin Interaction ◽  
Operator Representation ◽  
One Dimensional

Using Heisenberg model, the equations of motion for the dynamic properties of spin waves in three dimensions were obtained and solved analytically up to an exponential operator representation. Second order Suzuki Trotter decomposition method with evolution operator solution was applied to obtain the numerical solutions by making it closer to real spin systems. Computer based simulations on systems in micro canonical ensembles in constant-energy states were used to check the applicability of this model for one dimensional lattice by investigating the occurrence, temperature dependence and spin-spin interaction dependence of the spin waves. A visualization technique was used to show the existence of many spin wave components below the Curie temperature of the system. In the magnon dispersion curves all or most of the spin wave components could be recognized as peaks in the dynamic structure factor. Energy conservation of the algorithm is also shown.

scholarly journals Spin Waves in Two and Three Dimensional Magnetic Materials

2015 ◽  
Vol 49 ◽  
pp. 35-47 ◽  
Author(s):  
H.S. Wijesinhe ◽  
K.A.I.L. Wijewardena Gamalath
Keyword(s):  
Dynamic Properties ◽  
Equations Of Motion ◽  
Spin Waves ◽  
Three Dimensional ◽  
Dynamic Structure ◽  
Second Order ◽  
Three Dimensions ◽  
Operator Representation ◽  
Computer Based ◽  
Canonical Ensembles

The equations of motion for the dynamic properties of spin waves in three dimensions were obtained using Heisenberg model and solved for two and three dimensional lattices analytically up to an exponential operator representation. The second order Suzuki Trotter decomposition method was extended to incorporate second nearest interaction parameters into the numerical solution. Computer based simulations on systems in micro canonical ensembles in constant-energy states were used to check the applicability of this model for two dimensional lattice as well as three dimensional simple cubic and bcc lattices. In the magnon dispersion curves all or most of the spin wave components could be recognized as peaks in the dynamic structure factor presenting the variation of energy transfer with respect to momentum transfer of spin waves. Second order Suzuki Trotter algorithm used conserved the energy.

scholarly journals Weakly-Interacting Bose-Bose Mixtures from the Functional Renormalisation Group

2021 ◽  
Author(s):  
Felipe Isaule ◽  
Ivan Morera
Keyword(s):  
Three Dimensional ◽  
Renormalisation Group ◽  
Bose Gases ◽  
Infinite Population ◽  
Weakly Interacting ◽  
Complete Discussion ◽  
Population Imbalance ◽  
Ground State Energies ◽  
Detailed Presentation ◽  
Good Agreement

We provide a detailed presentation of the functional renormalisation group (FRG) approach to weakly-interacting Bose-Bose mixtures, including a complete discussion on the RG equations. To test this approach, we examine thermodynamic properties of balanced three-dimensional Bose-Bose gases at zero and finite temperatures and find a good agreement with related works. We also study ground-state energies of repulsive Bose polarons by examining mixtures in the limit of infinite population imbalance. Finally, we discuss future applications of the FRG to novel problems in Bose-Bose mixtures and related systems.

Study of Sedimentation Velocity of Block Copolymer Micelles

1993 ◽  
Vol 58 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Minmin Tian ◽  
C. Ramireddy ◽  
Stephen E. Webber ◽  
Petr Munk
Keyword(s):  
Block Copolymer ◽  
Methacrylic Acid ◽  
Mixed Solvent ◽  
Hard Spheres ◽  
Sedimentation Velocity ◽  
Hydrodynamic Coefficient ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Size Heterogeneity ◽  
Good Agreement

No anomalies were observed during the measurement of sedimentation coefficients of block copolymer micelles formed by copolymers of styrene and methacrylic acid in a mixed solvent; 80 vol.% of dioxane and 20 vol.% of water. The shapes of the sedimenting boundaries suggest that the size heterogeneity of the micelles is small. Linear relations between 1/s and c were obtained. The value of the hydrodynamic coefficient κ was between 2 and 4 in a good agreement with the value 2.75 or 2.86 that was obtained by combining Burgers' or Fixman's values of the coefficient of the concentration dependence kvs for hard spheres with Einstein's value of [η] for spheres.

Interferential seeing monitor, a seeing monitor for atmospheric turbulence studies: calibration with the differential image motion monitor

2020 ◽  
Vol 500 (2) ◽  
pp. 1884-1888
Author(s):  
Mohammed Sabil ◽  
A Habib ◽  
Z Benkhaldoun
Keyword(s):  
Structure Function ◽  
Atmospheric Turbulence ◽  
Wave Structure ◽  
Image Motion ◽  
Phase Fluctuations ◽  
Amplitude Fluctuations ◽  
Focus Plane ◽  
Cross Calibration ◽  
Double Slit ◽  
Good Agreement

ABSTRACT In this work, we aim to calibrate an interferential seeing monitor (ISM), which is a testing instument used at astronomical sites. Its method is based on the study of the diffraction pattern produced by a Young’s double-slit at the focus plane of a telescope. This method allows us to obtain the wave structure function by taking into account both phase and amplitude fluctuations of the light wavefront. A phase seeing εϕ was assigned to phase fluctuations and an amplitude seeing εχ was assigned to amplitude fluctuations (scintillation phenomenon), which allows us to obtain both phase and amplitude fluctuations. The feasibility of the ISM method was demonstrated by numerical simulations presented in a previous work. In this work, we have conducted a cross-calibration campaign of the ISM with a differential image motion monitor (DIMM) over 16 nights at the Oukaimeden and Atlas Golf Marrakech Observatories. The goal of this campaign was to study the reliability of this new method. In this paper, we present the calibration measurements and a comparison between the seeing measured by the ISM (εϕ, εχ) and that obtained by the DIMM (εdimm). These results show good agreement between the phase- eeing εϕ and εdimm.

Static and Dynamic Structure of Molecular Monomers and Dimers of the Rare-earth Fluorides

2001 ◽  
Vol 56 (5) ◽  
pp. 381-385
Author(s):  
Z. Akdeniz ◽  
M . Gaune-Escard ◽  
M. P. Tosi
Keyword(s):  
Rare Earth ◽  
Bond Length ◽  
Geometrical Structure ◽  
Vibrational Mode ◽  
Dynamic Structure ◽  
Molecular Shape ◽  
Proposed Model ◽  
Infrared Studies ◽  
Charged Clusters ◽  
Good Agreement

Abstract We determine a model of the ionic interactions in RF3 compounds, where R is a rare-earth element in the series from La to Lu, by an analysis of data on the bond length and the vibrational mode frequencies of the PrF3, GdF3 and HoF3 molecular monomers. All RF3 monomers are predicted to have a pyramidal shape, displaying a progressive flattening of the molecular shape in parallel with the lanthanide contraction of the bond length. The vibrational frequencies of all monomers are calculated, the results being in good agreement with the data from infrared studies of matrix-isolated molecules. We also evaluate the geometrical structure and the vibrational spectrum of the La2F6 and Ce2F6 dimers, as a further test of the proposed model. -PACS 36.40.Wa (Charged clusters)

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