ﻻ يوجد ملخص باللغة العربية
We study antiferromagnetic spin--1/2 Heisenberg ladders, comprised of $n_c$ chains ($2 leq n_c leq 6$) with ratio $J_{bot}/J_{|}$ of inter-- to intra--chain couplings. From measurements of the correlation function we deduce the correlation length $xi(T)$. For even $n_c$, the static structure factor exhibits a peak at a temperature below the corresponding spin gap. Results for isotropically coupled ladders ($J_{bot}/J_{|} = 1$) are compared to those for the single chain and the square lattice. For $J_{bot}/J_{|} leq 0.5$, the correlation function of the two--chain ladder is in excellent agreement with analytic results from conformal field theory, and $xi(T)$ exhibits simple scaling behavior.
The ground state properties of spin-polarized deuterium (D$downarrow$) at zero temperature are obtained by means of the diffusion Monte Carlo calculations within the fixed-node approximation. Three D$downarrow$ species have been investigated (D$downa
Interacting quantum spin models are remarkably useful for describing different types of physical, chemical, and biological systems. Significant understanding of their equilibrium properties has been achieved to date, especially for the case of spin m
This work expands recent investigations in the field of spin-polarized tritium (T$downarrow$) clusters . We report the results for the ground state energy and structural properties of large T$downarrow$ cl usters consisting of up to 320 atoms. All ca
The `dynamic Hubbard Hamiltonian describes interacting fermions on a lattice whose on-site repulsion is modulated by a coupling to a fluctuating bosonic field. We investigate one such model, introduced by Hirsch, using the determinant Quantum Monte C
We study the effect of inter-ladder ferromagnetic (FM) coupling in spin-1/2 two-leg ladders with antiferromagnetic (AFM) legs and rungs interactions using the stochastic series expansion quantum Monte Carlo. We have compared the results with the expe