ar X iv : c on d - m at / 9 50 50 89 v 1 1 9 M ay 1 99 5 Ground state properties of dissipative two state system coupled to phonons

ar X iv : c on d - m at / 9 30 50 01 v 1 3 M ay 1 99 3 One - dimensional asymmetrically coupled maps with defects

ar X iv : c on d - m at / 9 50 50 20 v 1 4 M ay 1 99 5 Frustration - how it can be measured

A misfit parameter is used to characterize the degree of frustration of ordered and disordered systems. It measures the increase of the ground-state energy due to frustration in comparison with that of a relevant reference state. The misfit parameter is calculated for various spin-glass models. It allows one to compare these models with each other. The extension of this concept to other combina...

ar X iv : c on d - m at / 9 50 60 18 v 1 5 J un 1 99 5 Hartree - Fock ground state of the composite fermion metal

Within the Hartree-Fock approximation the ground state of the composite fermion metal is found. We observe that the single-particle energy spectrum is dominated by the logarithmic interaction exchange term which leads to an infinite jump of the singleparticle energy at the Fermi momentum. It is shown that the Hartree-Fock result brings no corrections to the RPA Fermi velocity.

ar X iv : c on d - m at / 9 50 40 93 v 1 2 4 A pr 1 99 5 An Upsilon Point in a Spin Model

We present analytic evidence for the occurrence of an upsilon point, an infinite checkerboard structure of modulated phases, in the ground state of a spin model. The structure of the upsilon point is studied by calculating interface–interface interactions using an expansion in inverse spin anisotropy. pacs: 05.50.+q 64.40.Cn 75.10.Hk Typeset using REVTEX 1

ar X iv : c on d - m at / 9 50 81 21 v 1 2 6 A ug 1 99 5 On Quantum Solitons in the Sawtooth Lattice

We study the sawtooth lattice of a coupled spin 1/2 Heisenberg system, a variant of the railroad trestle lattice. The ground state of this system is twofold degenerate with periodic boundary conditions and supports kink antikink excitations, which are distinct in this case, unlike the railroad trestle lattice. The resulting low temperature thermodynamics is compared with the recently discovered...