Physics – Condensed Matter – Strongly Correlated Electrons
Scientific paper
1998-04-07
Physics
Condensed Matter
Strongly Correlated Electrons
28 pages, Latex, 2 postscript figures
Scientific paper
10.1103/PhysRevB.58.6394
The coupled cluster method (CCM) is a well-known method of quantum many-body theory, and here we present an application of the CCM to the spin-half J_1--J_2 quantum spin model with nearest- and next-nearest-neighbour interactions on the linear chain and the square lattice. We present new results for ground-state expectation values of such quantities as the energy and the sublattice magnetisation. The presence of critical points in the solution of the CCM equations, which are associated with phase transitions in the real system, is investigated. Completely distinct from the investigation of the critical points, we also make a link between the expansion coefficients of the ground-state wave function in terms of an Ising basis and the CCM ket-state correlation coefficients. We are thus able to present evidence of the breakdown, at a given value of J_2/J_1, of the Marshall-Peierls sign rule which is known to be satisfied at the pure Heisenberg point (J_2 = 0) on any bipartite lattice. For the square lattice, our best estimates of the points at which the sign rule breaks down and at which the phase transition from the antiferromagnetic phase to the frustrated phase occurs are, respectively, given (to two decimal places) by J_2/J_1 = 0.26 and J_2/J_1 = 0.61.
Bishop Raymond F.
Farnell Damian J. J.
Parkinson John B.
No associations
LandOfFree
Phase Transitions in the Spin-Half J_1--J_2 Model does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Phase Transitions in the Spin-Half J_1--J_2 Model, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Phase Transitions in the Spin-Half J_1--J_2 Model will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-433964