207 citations · 2.5k across the 69 of their papers we have counts for
7 papers · 1 filter
Series Expansions for Variable Electron Density
Zheng Weihong, C. J. Hamer, J. Oitmaa +1
We have developed a series expansion method for calculating the zero-temperature properties of lattice electron models for variable electron density, i.e. for finite doping away fr…
Critical dynamics of singlet and triplet excitations in strongly frustrated spin systems
O. P. Sushkov, J. Oitmaa, Zheng Weihong
New data for the two-dimensional J1-J2 model shows that the critical points for singlet and triplet excitations near J2/J1=0.38 are very close together, or coincident. We propose t…
Realization of a large J_2 quasi-2D spin-half Heisenberg system: Li2VOSiO4
H. Rosner, R. R. P. Singh, W. H. Zheng +3
Exchange couplings are calculated for Li2VOSiO4 using LDA. While the sum of in-plane couplings J_1 + J_2 = 9.5 \pm 1.5 K and the inter-plane coupling J_{perp} \sim 0.2 - 0.3 K agre…
The Phase Diagram of the Shastry-Sutherland Antiferromagnet
Zheng Weihong, J. Oitmaa, C. J. Hamer
The Shastry-Sutherland model, which provides a representation of the magnetic properties of SrCu(BO), has been studied by series expansion methods at T=0. Our results s…
Two-dimensional randomly-frustrated spin 1/2 Heisenberg model
J. Oitmaa, O. P. Sushkov
We investigate the properties of S=1/2 Heisenberg clusters with random frustration using exact diagonalizations. This is a model for a quantum spin glass. We show that the average…
Phase Diagram of the Spin-Orbital model on the Square Lattice
E. Zasinas, O. P. Sushkov, J. Oitmaa
We study the phase diagram of the spin-orbital model in both the weak and strong limits of the quartic spin-orbital exchange interaction. This allows us to study quantum phase tran…
Series study of the One-dimensional S-T Spin-Orbital Model
Weihong Zheng, J. Oitmaa
We use perturbative series expansions about a staggered dimerized ground state to compute the ground state energy, triplet excitation spectra and spectral weight for a one-dimensio…