Changing shapes: adiabatic dynamics of composite solitary waves

We discuss the solitary wave solutions of a particular two-component scalar field model in two-dimensional Minkowski space. These solitary waves involve one, two or four lumps of energy. The adiabatic motion of these composite non-linear non-dispersive waves points to variations in shape.Comment: 21 pages, 15 figures. To appear in Physica D: Nonlinear Phenomen

Absence of re-entrant phase transition of the antiferromagnetic Ising model on the simple cubic lattice: Monte Carlo study of the hard-sphere lattice gas

We perform the Monte Carlo simulations of the hard-sphere lattice gas on the simple cubic lattice with nearest neighbour exclusion. The critical activity is estimated, $z_{\rm c} = 1.0588 \pm 0.0003$. Using a relation between the hard-sphere lattice gas and the antiferromagnetic Ising model in an external magnetic field, we conclude that there is no re-entrant phase transition of the latter on the simple cubic lattice.Comment: 13 pages(4 LaTeX figures included), EDRUSBA-94092

Ferroelectrical spin wave resonance

New phenomenon is experimentally identified: ferroelectrical spin wave resonance (FE SWR), which consist in characteristic splitting of vibration (electronic-vibration) levels in optical spectra of interacting localized centers. Spectral positions of ESWR lines are determined in linear approach by quadratic dispersion law. It has been found that the values of resonance mode amplitudes are inversely proportional to mode numbers (by low excitation level). The prediction that Raman-ESWR and IR-ESWR are characterized by splitting constants with different values has been confirmed. Their ratio is approximately equal two (by the frequencies of zero modes reduced to the same value). It is independent argument for FE SWR identification.Comment: in russia

Correlation Effect on Peierls Transition

The effect of correlation on Peierls transition, which is accompanied by a dimerization, t_d, of a bond alternation for transfer energy, has been examined for a half-filled one-dimensional electron system with on-site repulsive interaction (U). By applying the renormalization group method to the interaction of the bosonized Hamiltonian, the dimerization has been calculated variationally and self-consistently with a fixed electron-phonon coupling constant (\lambda) and it is shown that t_d takes a maximum as a function of U. The result is examined in terms of charge gap and spin gap and is compared with that of the numerical simulation by Hirsch [Phys. Rev. Lett 51 (1983) 296]. Relevance to the spin Peierls transition in organic conductors is discussed.Comment: 4 pages, 4 figures, to be published in J. Phys. Soc. Jpn. 71 No.3 (2002