arXiv subjects
Publications and source records attributed to Mai Suan Li.
The Go model is extended to the case when the non-native contact energies may be either attractive or repulsive. The folding temperature is found to increase with the energy of non-native contacts. The repulsive non-native contact energies may lead to folding at T=0 for some two-dimensional sequences and to reduction in complexity of disconnectivity graphs for local energy minima.
A three-dimensional lattice of the Josephson junctions with a finite self-conductance is employed to model the ceramic superconductors. The nonlinear ac susceptibility and the compensation effect are studied by Monte Carlo simulations in this model. The compensation effect is shown to be due to the existence of the chiral glass phase. We demonstrate, in agreement with experiments, that this effect may be present in the ceramic superconductors which show the paramagnetic Meissner effect.
Possible occurrence of an equilibrium thermodynamic phase with a spontaneously broken time-reversal symmetry is studied in a model ceramic superconductor with anisotropic pairing symmetry. It is shown by Monte Carlo simulations that such a ``chiral-glass'' phase is truly stable even under the influence of screening. Existence of frustration in zero external field, arising from the d-wave pairing symmetry of high-T_c superconductors, is essential to realize this phase. Via a finite-size scaling analysis, critical exponents associated with the chiral-glass transition are estimated to be ν_CG=1.3\pm 0.2 and η_CG=-0.2\pm 0.2. These values turn out to be close to those of the Ising spin glass. Phase diagram of the model is constructed and the implications to experiments are discussed.