Calculation of the singlet-triplet gap of the antiferromagnetic Heisenberg model on a ladder
M. Azzouz, Liang Chen, S. Moukouri
1994
Physical Review B (Condensed Matter)
The ground state energy and the singlet-triplet energy gap of the antiferromagnetic Heisenberg model on a ladder is investigated using a mean field theory and the density matrix renormalization group. Spin wave theory shows that the corrections to the local magnetization are infinite. This indicates that no long range order occurs in this system. A flux-phase state is used to calculate the energy gap as a function of the transverse coupling, J_, in the ladder. It is found that the gap is linear
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... in J_ for J_≫ 1 and goes to zero for J_→ 0. The mean field theory agrees well with the numerical results.
doi:10.1103/physrevb.50.6233
pmid:9976997
fatcat:oztffbruwzdt3aqqfx4tzfyir4