期刊
PHYSICAL REVIEW B
卷 85, 期 3, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.85.035130
关键词
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资金
- Austrian Science Fund (FWF) [W1210]
- Research Foundation Flanders
- ERC
- FWF SFB
- Austrian Science Fund (FWF) [W1210] Funding Source: Austrian Science Fund (FWF)
We study a matrix product state algorithm to approximate excited states of translationally invariant quantum spin systems with periodic boundary conditions. By means of a momentum eigenstate ansatz generalizing the one of Ostlund and Rommer [see S. Ostlund and S. Rommer, Phys. Rev. Lett. 75, 3537 ( 1995); S. Rommer and S. Ostlund, Phys. Rev. B 55, 2164 (1997)], we separate the Hilbert space of the system into subspaces with different momentum. This gives rise to a direct sum of effective Hamiltonians, each one corresponding to a different momentum, and we determine their spectrum by solving a generalized eigenvalue equation. Surprisingly, many branches of the dispersion relation are approximated to a very good precision. We benchmark the accuracy of the algorithm by comparison with the exact solutions and previous numerical results for the quantum Ising, the antiferromagnetic Heisenberg spin-1/2, and the bilinear-biquadratic spin-1 models.
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