scholarly journals Complete catalog of ground-state diagrams for the general three-state lattice-gas model with nearest-neighbor interactions on a square lattice

2019 ◽  
Vol 21 (11) ◽  
pp. 6216-6223 ◽  
Author(s):  
Daniel Silva ◽  
Per Arne Rikvold
Keyword(s):  
Phase Diagrams ◽  
Ground State ◽  
Lattice Gas ◽  
Nearest Neighbor ◽  
Square Lattice ◽  
Temperature Phase ◽  
Zero Temperature ◽  
Dimensional Parameter ◽  
State Diagrams ◽  
Solid Foundation

The fifteen topologically different zero-temperature phase diagrams in the model's full, five-dimensional parameter space provide a solid foundation for studies at finite temperatures.

COUPLED CLUSTER TREATMENTS OF QUANTUM MAGNETS: TWO EXAMPLES

2003 ◽  
Vol 17 (28) ◽  
pp. 5347-5365 ◽  
Author(s):  
SVEN E. KRÜGER ◽  
DAMIAN J. J. FARNELL ◽  
JOHANNES RICHTER
Keyword(s):  
Ground State ◽  
Quantum Monte Carlo ◽  
Quantum Spin ◽  
Square Lattice ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Temperature Phase ◽  
Nearest Neighbour ◽  
Zero Temperature ◽  
Quantum Spin Models

In this article we study the ground-state properties of two square-lattice Heisenberg quantum spin models with competing bonds using a high-order coupled cluster treatment. The first model is a spin-half model with competing nearest-neighbour bonds with and without frustration. We discuss the influence of quantum fluctuations on the ground-state phase diagram and in particular on the nature of the zero-temperature phase transitions from phases with collinear magnetic order at small frustration to phases with noncollinear spiral order at large frustration. The second model is a highly frustrated ferrimagnet, which contains one sublattice (A) entirely populated with spin-one spins and an other sublattice (B) entirely populated with spin-half spins. Sublattice A sites are nearest-neighbours to sublattice B sites and vice versa and frustration is introduced by next-nearest-neighbour bonds. The model shows two collinear ordered phases and a noncollinear phase in which (classically) the spin-one spins are allowed to cant at an angle. Both examples show that the coupled-cluster method is able to describe the zero-temperature transitions well and provides a consistent description of collinear, noncollinear, and disordered phases, for cases in which other standard techniques (e.g. the quantum Monte Carlo technique for spin systems which are frustrated) are not applicable.

GROUND STATE OF THE 2D EXTENDED HUBBARD MODEL WITH MORE THAN NEAREST-NEIGHBOR INTERACTIONS

2012 ◽  
Vol 26 (29) ◽  
pp. 1250156 ◽  
Author(s):  
S. HARIR ◽  
M. BENNAI ◽  
Y. BOUGHALEB
Keyword(s):  
Phase Diagram ◽  
Hubbard Model ◽  
Ground State ◽  
State Energy ◽  
Nearest Neighbor ◽  
Finite Size ◽  
Square Lattice ◽  
Extended Hubbard Model ◽  
Eigenvalues And Eigenvectors ◽  
Repulsion Energy

We investigate the ground state phase diagram of the two dimensional Extended Hubbard Model (EHM) with more than Nearest-Neighbor (NN) interactions for finite size system at low concentration. This EHM is solved analytically for finite square lattice at one-eighth filling. All eigenvalues and eigenvectors are given as a function of the on-site repulsion energy U and the off-site interaction energy Vij. The behavior of the ground state energy exhibits the emergence of phase diagram. The obtained results clearly underline that interactions exceeding NN distances in range can significantly influence the emergence of the ground state conductor–insulator transition.

Three-State Lattice-Gas Model of H-S on Pt(111)

1987 ◽  
Vol 111 ◽  
Author(s):  
Per Arne Rikvold ◽  
Joseph B. Collins ◽  
G. D. Hansen ◽  
J. D. Gunton ◽  
E. T. Gawlinski
Keyword(s):  
Adsorption Isotherms ◽  
Ground State ◽  
Lattice Gas ◽  
Nearest Neighbor ◽  
Numerical Study ◽  
Finite Size ◽  
Lateral Interaction ◽  
Finite Size Scaling ◽  
Enhanced Adsorption ◽  
Good Agreement

AbstractWe consider a three-state lattice-gas with nearest-neighbor interactions on a triangular lattice as a model for multicomponent chemi- and physisorption. By varying the lateral interaction constants between the adsorbate particles, this model can be made to exhibit either enhanced adsorption or poisoning (inhibited adsorption). We discuss here the conditions on the interaction constants that lead to poisoning. We present the results of a ground-state calculation and detailed numerical study of the phase diagram for a set of interactions that exhibits poisoning. We calculate the phase diagrams and adsorption isotherms by the finite-size scaling transfer-matrix method. We consider the result as a simple model for the coadsorption of Sulphur and Hydrogen on a Platinum (111) surface, with interaction constants estimated from experimental data. The resulting adsorption isotherms are in good agreement with experimental results.

INTERFACE INSTABILITY IN DRIVEN LATTICE GASES

Fractals ◽  
1993 ◽  
Vol 01 (04) ◽  
pp. 954-958 ◽  
Author(s):  
G. SZABÓ ◽  
A. SZOLNOKI ◽  
T. ANTAL ◽  
I. BORSOS
Keyword(s):  
Lattice Gas ◽  
Nearest Neighbor ◽  
Interfacial Instability ◽  
Lattice Gases ◽  
Square Lattice ◽  
Wave Number ◽  
Material Transport ◽  
Interface Instability ◽  
Amplification Rate ◽  
Lattice Gas Models

In driven lattice-gas models, the enhanced material transport along the interfaces results in an instability of the planar interfaces and leads to the formation of multistrip states. To study the interfacial instability, Monte Carlo simulations are performed on different square lattice-gas models. The amplification rate of a periodic perturbation depends on the wave number k; it has a positive maximum at a characteristic value of k on the analogy of the Mullins-Sekerka instability. Significant differences have been found in the dependence of amplification rate on k when comparing the systems with nearest neighbor repulsive and nearest and next-nearest neighbor attractive interactions. The results agree qualitatively with theories neglecting the fluctuations.

scholarly journals Проявление фрустраций основного состояния двумерной разбавленной модели Изинга в магнитокалорическом эффекте

2020 ◽  
Vol 62 (9) ◽  
pp. 1549
Author(s):  
А.В. Шадрин ◽  
В.А. Улитко ◽  
Ю.Д. Панов
Keyword(s):  
Ground State ◽  
Square Lattice ◽  
Zero Temperature ◽  
Magnetic Entropy ◽  
Nonmagnetic Impurities ◽  
Weak Exchange ◽  
Dilute Ising Model ◽  
High Concentrations ◽  
Using Data ◽  
Ferromagnetic Ordering

The magnetocaloric effect is considered in the 2D dilute Ising model for various ratios of the parameters of inter-site repulsion of nonmagnetic impurities and exchange interaction. Numerical simulations using the classical Monte Carlo method on a square lattice shows that in the case of weak exchange at sufficiently high concentrations of nonmagnetic impurities, long-range ferromagnetic ordering is destroyed with the formation of isolated spin clusters in the ground state of the system. This leads to the appearance of a paramagnetic response of the system at zero temperature and a nonzero entropy of the ground state. In the paper, we discuss the possibility of detecting the frustration of the ground state using data on changes in magnetic entropy.

SPIN-2 ISING MODEL ON THE BILAYER BETHE LATTICE

2008 ◽  
Vol 22 (24) ◽  
pp. 4189-4203 ◽  
Author(s):  
ERHAN ALBAYRAK ◽  
SEYMA AKKAYA ◽  
SABAN YILMAZ
Keyword(s):  
Phase Diagrams ◽  
Ground State ◽  
Nearest Neighbor ◽  
Lower Layer ◽  
Bethe Lattice ◽  
Branching Ratio ◽  
Interlayer Coupling ◽  
Coupling Constants ◽  
First Order Phase ◽  
Over The Top

A spin-2 system consisting of two layers of Bethe lattices each with a branching ratio of q Ising spins was analyzed by the use of the exact recursion relations in a pairwise approach. The upper layer interacting with nearest-neighbor (NN) bilinear interaction J1 is laid over the top of the lower layer interacting with bilinear NN interaction J2, and the two layers are tied together via the bilinear interaction between the vertically aligned adjacent NN spins denoted as J3. The study of the ground state phase diagrams on the (J2/|J3|, J1/|J3|) plane with J3>0 and J3<0 and on the (J2/J1, J3/q J1) plane with J1>0 has yielded five distinct ground state configurations. The temperature dependent phase diagrams are obtained for the case with intralayer coupling constants of the two layers with ferromagnetic type J1 and J2>0, and the interlayer coupling constant of the layers with either ferromagnetic J3>0 or antiferromagnetic type J3<0 on the (kT/J1, J3/J1) planes for given values of the J2/J1 for various values of the coordination numbers. As a result, we have found that the model presents both second- and first-order phase transitions, therefore, tricritical points.

THE EFFECT OF A BOND-SITE INTERACTION ON THE GROUND-STATE INSTABILITIES OF THE ONE-DIMENSIONAL HUBBARD MODEL

1995 ◽  
Vol 09 (12) ◽  
pp. 1503-1514 ◽  
Author(s):  
F.D. BUZATU
Keyword(s):  
Hubbard Model ◽  
Ground State ◽  
Temperature Phase ◽  
Zero Temperature ◽  
Perturbative Approach ◽  
Dimensional Lattice ◽  
One Dimensional ◽  
Low Concentrations ◽  
The One ◽  
Temperature Phase Diagram

The ground-state instabilities for a one-dimensional lattice system of electrons with onsite (Hubbard) and bond-site (hopping) interactions are analyzed in a perturbative approach. The zero temperature phase diagram at different band fillings is drawn; an attractive (repulsive) bond-site interaction favors the appearance of a superconductor state at low concentrations of electrons (holes). A comparison with the exact results for the Hubbard model and previous works for particular cases is also discussed.

Onsager reaction field theory applied to the phase diagram of Heisenberg chain with ferromagnetic long-range interaction and antiferromagnetic nearest-neighbor interaction

2021 ◽  
Vol 35 (06) ◽  
pp. 2150080
Author(s):  
Yuan Chen ◽  
Xiuzhi Zhang ◽  
Wenan Li ◽  
Jipei Chen
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Long Range ◽  
Nearest Neighbor ◽  
Temperature Phase ◽  
Zero Temperature ◽  
Neighbor Interaction ◽  
Range Interaction ◽  
Reaction Field ◽  
The One

Onsager reaction field theory is used to investigate the one-dimensional ferromagnetic long-range interacting spin chain with the antiferromagnetic nearest-neighbor interaction (NNI) [Formula: see text]. The ferromagnetic long-range interactions considered in this paper decay as [Formula: see text] with the distance [Formula: see text] between lattice sites. It is found that both the zero temperature and finite-temperature phase diagrams of the system are strongly affected by the interplay between ferromagnetic long-range and antiferromagnetic NNIs. The critical temperature and the uniform susceptibility are obtained as a function of [Formula: see text] and [Formula: see text]. At finite temperatures and in the region [Formula: see text] in which [Formula: see text] is dependent of [Formula: see text], the ferromagnetic-paramagnetic phase transition survives for [Formula: see text] and no phase transition exists for [Formula: see text]. At [Formula: see text], the ferromagnetic-antiferromagnetic phase transition happens at zero temperature for [Formula: see text]. The ground state of the system keeps ferromagnetic when [Formula: see text]. But for [Formula: see text], the system becomes antiferromagnetic at all temperatures.

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