ar X iv : c on d - m at / 9 70 62 16 v 1 2 0 Ju n 19 97 Transfer matrix of a spherical scatterer

ar X iv : h ep - l at / 9 70 60 19 v 1 2 6 Ju n 19 97 BUTP – 97 / 16 Properties of Renormalization Group Transformations 1

We describe some properties of Renormalization Group transformations. Especially we show why some of the RG transformations have redundant eigenoperators with eigenvalues that cannot be determined by simple dimensional analysis and give the corresponding formulae. Work supported in part by Schweizerischer Nationalfonds

ar X iv : c on d - m at / 9 70 61 16 v 1 1 2 Ju n 19 97 RANDOM TILING TRANSITION IN THREE DIMENSIONS

Three-dimensional icosahedral random tilings are studied in the semi-entropic model. We introduce a global energy measure defined by the variance of the quasi-lattice points in orthogonal space. The specific heat shows a pronounced Schottky type anomaly, but it does not diverge with sample size. The flip susceptibility as defined by Dotera and Steinhardt [Phys. Rev. Lett. 72, 1670 (1994)] diver...

ar X iv : m at h - ph / 9 90 70 23 v 1 2 8 Ju l 1 99 9 EIGENFUNCTIONS , TRANSFER MATRICES , AND ABSOLUTELY CONTINUOUS SPECTRUM OF ONE - DIMENSIONAL SCHRÖDINGER OPERATORS

In this paper, we will primarily discuss one-dimensional discrete Schrödinger operators (hu)(n) = u(n + 1) + u(n − 1) + V (n)u(n) (1.1D) on ℓ 2 (Z) (and the half-line problem, h + , on ℓ 2 ({n ∈ Z | n > 0}) ≡ ℓ 2 (Z +)) with u(0) = 0 boundary conditions. We will also discuss the continuum analog (Hu)(x) = −u ′′ (x) + V (x)u(x) (1.1C) on L 2 (R) (and its half-line problem, H + , on L 2 (0, ∞) wi...

ar X iv : c on d - m at / 9 70 62 99 v 1 3 0 Ju n 19 97 Coupled Cluster Treatment of the XY model

We study quantum spin systems in the 1D, 2D square and 3D cubic lattices with nearest-neighbour XY exchange. We use the coupled-cluster method (CCM) to calculate the ground-state energy, the T = 0 sublattice magnetisation and the excited state energies, all as functions of the anisotropy parameter γ. We consider S = 1/2 in detail and give some results for higher S. In 1D these results are compa...

ar X iv : n uc l - th / 9 80 60 97 v 1 2 9 Ju n 19 98 3 P 2 - 3 F 2 pairing in neutron matter with modern nucleon - nucleon potentials