# Improved harmonic approximation and the 2D Ising model at T ≠ Tc and h ≠ 0

@article{Iucci2002ImprovedHA, title={Improved harmonic approximation and the 2D Ising model at T ≠ Tc and h ≠ 0}, author={An{\'i}bal Iucci and Carlos M. Na'on}, journal={Journal of Physics A}, year={2002}, volume={35}, pages={8005-8012} }

We propose a new method to determine the unknown parameter associated with a self-consistent harmonic approximation. We check the validity of our technique in the context of the sine-Gordon model. As a non-trivial application we consider the scaling regime of the 2D Ising model away from the critical point and in the presence of a magnetic field h. We derive an expression that relates the approximate correlation length ξ, T − Tc and h.

## References

SHOWING 1-10 OF 40 REFERENCES

### Local time-dependent perturbation in Luttinger liquid.

- PhysicsPhysical review letters
- 1993

The response of the Luttinger liquid to a local potential is studied at zero temperature and the backscattering from the potential contributes to the core-hole Green's function G(t) the factor (t 0 /t) 1/8 ―a universal (potential independent) decay law.

### MASS SCALE IN THE SINE–GORDON MODEL AND ITS REDUCTIONS

- Physics
- 1995

Known Bethe ansatz results about the sine–Gordon factorized scattering are reinterpreted in terms of perturbed conformal field theory. We obtain an exact relation between the ultraviolet and…

### Central charge and universal combinations of amplitudes in two-dimensional theories away from criticality.

- PhysicsPhysical review letters
- 1988

The universal singular free energy per correlation volume fs2 is equal to -(c12)(2-)(1-)-1, where c is the central charge of the theory at criticality, is the usual specific-heat exponent, and is defined (for >0) in terms of the second moment of the energy correlations.

### Friedel oscillations for interacting fermions in one dimension.

- PhysicsPhysical review letters
- 1995

Friedel oscillations in one-dimensional electron liquid for arbitrary electron-electron interaction and arbitrary impurity strength are studied and a slower decay is found at intermediate distances from the impurity, with a crossover to the asymptotic x-g law.

### Thermodynamic Bethe ansatz in relativistic models: Scaling 3-state potts and Lee-Yang models

- Physics
- 1990

### Self-consistent calculation of statics and dynamics of the roughening transition

- Materials Science
- 1978

Statics and dynamics of the modified kinetic discrete Gaussian model are treated selfconsistently using a Gaussian probability assumption. A non-trivial roughening temperatureTR is found in exactly…

### The local sine - Gordon model

- Physics
- 1996

Effects of spatial inhomogeneity in the one-dimensional quantum sine - Gordon model are treated by use of the variational Gaussian wave-functional method. The properties of the ground state and the…