arXiv subjects

U. Blasum

Publications and source records attributed to U. Blasum.

3 recordsLinked to original sources

arXiv1997

Ground state properties of solid-on-solid models with disordered substrates

We study the glassy super-rough phase of a class of solid-on-solid models with a disordered substrate in the limit of vanishing temperature by means of exact ground states, which we determine with a newly developed minimum cost flow algorithm. Results for the height-height correlation function are compared with analytical and numerical predictions. The domain wall energy of a boundary induced step grows logarithmically with system size, indicating the marginal stability of the ground state, and the fractal dimension of the step is estimated. The sensibility of the ground state with respect to infinitesimal variations of the quenched disorder is analyzed.

cond-mat.dis-nn↗

arXiv1996

The critical exponents of the two-dimensional Ising spin glass revisited: Exact Ground State Calculations and Monte Carlo Simulations

The critical exponents for $T\to0$ of the two-dimensional Ising spin glass model with Gaussian couplings are determined with the help of exact ground states for system sizes up to $L=50$ and by a Monte Carlo study of a pseudo-ferromagnetic order parameter. We obtain: for the stiffness exponent $y(=θ)=-0.281\pm0.002$, for the magnetic exponent $δ=1.48 \pm 0.01$ and for the chaos exponent $ζ=1.05\pm0.05$. From Monte Carlo simulations we get the thermal exponent $ν=3.6\pm0.2$. The scaling prediction $y=-1/ν$ is fulfilled within the error bars, whereas there is a disagreement with the relation $y=1-δ$.

cond-mat↗

arXiv1996

Using network-flow techniques to solve an optimization problem from surface-physics

The solid-on-solid model provides a commonly used framework for the description of surfaces. In the last years it has been extended in order to investigate the effect of defects in the bulk on the roughness of the surface. The determination of the ground state of this model leads to a combinatorial problem, which is reduced to an uncapacitated, convex minimum-circulation problem. We will show that the successive shortest path algorithm solves the problem in polynomial time.

cond-mat↗