Variational matrix product ansatz for dispersion relations

Author(s): J. Haegeman, B. Pirvu, D.J. Weir, J. I. Cirac, T. J. Osborne, H. Verschelde, F. Verstraete

Journal: Phys. Rev. B

Volume: 85

Page(s): 5 pp.

Year: 2012

DOI Number: 10.1103/PhysRevB.85.100408

Link: Link to publication


A variational ansatz for momentum eigenstates of translation-invariant quantum spin chains is formulated. The matrix product state ansatz works directly in the thermodynamic limit and allows for an efficient implementation (cubic scaling in the bond dimension) of the variational principle. Unlike previous approaches, the ansatz includes topologically nontrivial states (kinks, domain walls) for systems with symmetry breaking. The method is benchmarked using the spin-½ XXZ antiferromagnet and the spin-1 Heisenberg antiferromagnet, and we obtain surprisingly accurate results.


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