Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical review. B, Condensed matter

Real-space dynamic renormalization group: Systematics for T>~Tc

Gene F. Mazenko, Oriol T. Valls

Published Aug 1, 1981• 19 citations
Publisher

Abstract

In this paper we systematize the real-space dynamic-renormalization-group method we developed elsewhere. We treat the two-dimensional kinetic Ising model with relaxational dynamics defined on a square lattice. We show how one can set up a systematic perturbation-theory expansion which treats the coupling between cells of spins as a small parameter. The novel feature of the expansion is that it provides a method for determining the appropriate effective interaction between spins in a set of uncoupled cells. By obtaining a good zeroth-order approximation for a set of uncoupled cells, one finds that the effective interaction between cells is reduced. Similar ideas are also applied to the dynamics of the problem and we indicate how one can obtain a good zeroth-order approximation in terms of the dynamics of uncoupled cells. We couple these perturbation theory ideas to the real-space dynamic-renormalization-group method and carry out explicit calculations of a variety of observable quantities including the magnetic susceptibility, specific heat, static structure factor, time-dependent spin-autocorrelation function, and the dynamic structure factor. In every case we obtain excellent results in keeping with the scaling behavior near the phase transition and the high-temperature limit.

DOI
10.1103/physrevb.24.1404

Related papers

Real-space dynamic renormalization group. III. Calculation of correlation functions

Gene F. Mazenko, J. E. Hirsch, Michael J. Nolan +1 more

The real-space dynamic renormalization group method developed in previous papers is applied to the kinetic Ising model defined on a square lattice. In particular we extend the formalism to the calculation of space- and time-dependent equilibrium averaged correlation functions. We find that conventional methods for implementing the real-space renormalization group via cumulant expansions in terms of the intercell coupling lead to correlation functions which decay algebraically in space at large distances in the disordered phase in qualitative disagreement with the known exponential decay. We indicate how one can develop new perturbation theory expansion methods which lead to the proper exponential decay at large distances and also lead to good quantitative results for other observable quantities like the magnetization, susceptibility, and single spin time autocorrelation function. As the result of a first-order calculation we obtain excellent results for the static critical exponents and a value of $z=1.79$ for the dynamic critical exponent. The critical exponents obtained from the correlation functions calculated using this method satisfy the proper static and dynamic scaling relations.

Physical review. B, Condensed matter•Feb 1, 1981•17 citations

Real-space dynamic renormalization group: Systematics T

Gene F. Mazenko, Oriol T. Valls

We extend our previous analysis of the two-dimensional kinetic Ising model using the real-space dynamic-renormalization-group (RSDRG) method to the ordered phase. This extension involves a discussion of spontaneous symmetry breaking within the context of a perturbative treatment using uncoupled cells as a zeroth-order approximation. This leads us to consider the introduction of an effective local magnetic field which simulates the average local order and necessitates the generalization of the RSDRG approach to the case of a finite magnetic field. We explain the role of the local order and proceed to calculate various observables. We note that our results match smoothly with our results for $T>~{T}_{c}$.

Physical review. B, Condensed matter•Jul 1, 1982•5 citations

Real-Space Renormalization Group Approach to the Kinetic Ising Model

Hiroshi Takano, Masuo Suzuki

A systematic real-space dynamic renormalization group method is proposed and it is applied to the kinetic Ising model on a triangular lattice. The coarse grained master equation is constructed by using the memory function formalism and the Markov approximation. The high temperature series renormalization group method proposed by Betts, Cuthiell and Plischke is extended for the present purpose to make a perturbation expansion in a self-consistent way with respect to all orders of interactions. Terms nonlocal in space appear in the coarse grained time-evolution operator in our approach, because of the memory effect accompanied with the coarse graining procedure. It is shown within the second order calculation that these nonlocal terms are irrelevant around the nontrivial fixed point. The values of the static exponent ν and dynamic exponent z are given by 1/ν = 0.99 and z = 2.23 from the present second order calculation. These results are quite reasonable.

Progress of Theoretical Physics•May 1, 1982•11 citations

Critical dynamics and renormalization-group methods for the kinetic Ising model

Gene F. Mazenko, Oriol T. Valls

The theory of the critical dynamics of the single spin-flip kinetic Ising model is examined. Various unproven assumptions and misconceptions are uncovered and discussed. In particular, we point out that the condition of detailed balance places important constraints on the renormalization-group analysis of this problem. The relationship among different fixed-point dynamical operators and dynamic universality classes is clarified. The role and convergence of perturbation-theory expansions which treat the bare coupling between cells as a small parameter in the real-space renormalization-group treatment are analyzed. We give reasons for believing that this approach cannot compete with methods using direct high-temperature expansions. We also comment on the usefulness of other methods in treating this problem.

Physical review. B, Condensed matter•Feb 1, 1985•14 citations

Real-space dynamic renormalization group. II. Simple examples

Gene F. Mazenko, Michael J. Nolan, Oriol T. Valls

The real-space renormalization-group method for the dynamics of critical phenomena introduced in the previous paper is applied to two calculations within the two-dimensional kinetic Ising model on a triangular lattice. In both cases a cumulant expansion in the intercell couplings is performed. In the first calculation are found the most general first-order recursion relations coupling neighboring cells. From these recursion relations is extracted the dynamic critical exponent $z=1.70$. While this is a reasonable first-order result, the results for the statics are not as satisfactory. In the second calculation it is shown how the terms that are generated at second order are important in determining the static results. We obtain at second order $z=2.22$, together with a critical coupling ${K}_{c}=0.251$ and a thermal critical index $\ensuremath{\nu}=0.950$.

Physical review. B, Condensed matter•Aug 1, 1980•19 citations

Renormalization-group study of the ferromagnetic Ising model on the triangular lattice

Chris Unger

The dynamic real-space renormalization group of Mazenko and Valls is applied to the zero-field ferromagnetic Ising model on the triangular lattice. Renormalization equations valid for all temperatures above the critical temperature ${T}_{c}$ are derived for the susceptibility, specific heat, structure factor, and correlation length. The magnetization is found for $T<{T}_{c}$. The critical exponents and amplitudes for these quantities are calculated. The agreement between the known static properties and the renormalization-group results is good to excellent, and shows that this renormalization-group method can accurately calculate nonuniversal, as well as universal, quantities on different lattices. The computed dynamic structure factor, however, exhibits nonmonotonic behavior as a function of temperature. This nonmonotonic behavior is conjectured to be due to approximations in determining the expansion parameters.

Physical review. B, Condensed matter•Aug 1, 1984•0 citations
In this paper we systematize the real-space dynamic-renormalization-group method we developed elsewhere. We treat the two-dimensional kinetic Ising model with relaxational dynamics defined on a square lattice. We show how one can set up a systematic perturbation-theory expansion which treats the coupling between cells of spins as a small parameter. The novel feature of the expansion is that it provides a method for determining the appropriate effective interaction between spins in a set of uncoupled cells. By obtaining a good zeroth-order approximation for a set of uncoupled cells, one finds that the effective interaction between cells is reduced. Similar ideas are also applied to the dynamics of the problem and we indicate how one can obtain a good zeroth-order approximation in terms of the dynamics of uncoupled cells. We couple these perturbation theory ideas to the real-space dynamic-renormalization-group method and carry out explicit calculations of a variety of observable quantities including the magnetic susceptibility, specific heat, static structure factor, time-dependent spin-autocorrelation function, and the dynamic structure factor. In every case we obtain excellent results in keeping with the scaling behavior near the phase transition and the high-temperature limit.
The real-space dynamic renormalization group method developed in previous papers is applied to the kinetic Ising model defined on a square lattice. In particular we extend the formalism to the calculation of space- and time-dependent equilibrium averaged correlation functions. We find that conventional methods for implementing the real-space renormalization group via cumulant expansions in terms of the intercell coupling lead to correlation functions which decay algebraically in space at large distances in the disordered phase in qualitative disagreement with the known exponential decay. We indicate how one can develop new perturbation theory expansion methods which lead to the proper exponential decay at large distances and also lead to good quantitative results for other observable quantities like the magnetization, susceptibility, and single spin time autocorrelation function. As the result of a first-order calculation we obtain excellent results for the static critical exponents and a value of z=1.79z=1.79z=1.79 for the dynamic critical exponent. The critical exponents obtained from the correlation functions calculated using this method satisfy the proper static and dynamic scaling relations.
We extend our previous analysis of the two-dimensional kinetic Ising model using the real-space dynamic-renormalization-group (RSDRG) method to the ordered phase. This extension involves a discussion of spontaneous symmetry breaking within the context of a perturbative treatment using uncoupled cells as a zeroth-order approximation. This leads us to consider the introduction of an effective local magnetic field which simulates the average local order and necessitates the generalization of the RSDRG approach to the case of a finite magnetic field. We explain the role of the local order and proceed to calculate various observables. We note that our results match smoothly with our results for T> TcT>~{T}_{c}T> Tc​.
A systematic real-space dynamic renormalization group method is proposed and it is applied to the kinetic Ising model on a triangular lattice. The coarse grained master equation is constructed by using the memory function formalism and the Markov approximation. The high temperature series renormalization group method proposed by Betts, Cuthiell and Plischke is extended for the present purpose to make a perturbation expansion in a self-consistent way with respect to all orders of interactions. Terms nonlocal in space appear in the coarse grained time-evolution operator in our approach, because of the memory effect accompanied with the coarse graining procedure. It is shown within the second order calculation that these nonlocal terms are irrelevant around the nontrivial fixed point. The values of the static exponent ν and dynamic exponent z are given by 1/ν = 0.99 and z = 2.23 from the present second order calculation. These results are quite reasonable.
The theory of the critical dynamics of the single spin-flip kinetic Ising model is examined. Various unproven assumptions and misconceptions are uncovered and discussed. In particular, we point out that the condition of detailed balance places important constraints on the renormalization-group analysis of this problem. The relationship among different fixed-point dynamical operators and dynamic universality classes is clarified. The role and convergence of perturbation-theory expansions which treat the bare coupling between cells as a small parameter in the real-space renormalization-group treatment are analyzed. We give reasons for believing that this approach cannot compete with methods using direct high-temperature expansions. We also comment on the usefulness of other methods in treating this problem.
The real-space renormalization-group method for the dynamics of critical phenomena introduced in the previous paper is applied to two calculations within the two-dimensional kinetic Ising model on a triangular lattice. In both cases a cumulant expansion in the intercell couplings is performed. In the first calculation are found the most general first-order recursion relations coupling neighboring cells. From these recursion relations is extracted the dynamic critical exponent z=1.70z=1.70z=1.70. While this is a reasonable first-order result, the results for the statics are not as satisfactory. In the second calculation it is shown how the terms that are generated at second order are important in determining the static results. We obtain at second order z=2.22z=2.22z=2.22, together with a critical coupling Kc=0.251{K}_{c}=0.251Kc​=0.251 and a thermal critical index $\ensuremath{\nu}=0.950$.
The dynamic real-space renormalization group of Mazenko and Valls is applied to the zero-field ferromagnetic Ising model on the triangular lattice. Renormalization equations valid for all temperatures above the critical temperature Tc{T}_{c}Tc​ are derived for the susceptibility, specific heat, structure factor, and correlation length. The magnetization is found for T<TcT<{T}_{c}T<Tc​. The critical exponents and amplitudes for these quantities are calculated. The agreement between the known static properties and the renormalization-group results is good to excellent, and shows that this renormalization-group method can accurately calculate nonuniversal, as well as universal, quantities on different lattices. The computed dynamic structure factor, however, exhibits nonmonotonic behavior as a function of temperature. This nonmonotonic behavior is conjectured to be due to approximations in determining the expansion parameters.