Quantum spin solver near saturation: QS$^3_{~}$

• URL: http://arxiv.org/abs/2107.00872v1
• Date: Fri, 2 Jul 2021 07:06:34 GMT
• Title: Quantum spin solver near saturation: QS$^3_{~}$
• Authors: Hiroshi Ueda, Seiji Yunoki, Tokuro Shimokawa
• Abstract summary: We develop a program package named QS$3$ [textipakj'u:-'es-kj'u:b] based on the (thick-restart) Lanczos method for analyzing spin-1/2 XXZ-type quantum spin models. We show the benchmark results of QS$3$ for the low-energy excitation dispersion of the isotropic Heisenberg model on the $10times10times10$ cubic lattice.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We develop a program package named QS$^{3}$ [\textipa{kj\'u:-\'es-kj\'u:b}] based on the (thick-restart) Lanczos method for analyzing spin-1/2 XXZ-type quantum spin models on spatially uniform/non-uniform lattices near fully polarized states, which can be mapped to dilute hardcore Bose systems. All calculations in QS$^{3}$, including eigenvalue problems, expectation values for one/two-point spin operators, and static/dynamical spin structure factors, are performed in the symmetry-adapted bases specified by the number $N_{\downarrow}$ of down spins and the wave number $\boldsymbol{k}$ associated with the translational symmetry without using the bit representation for specifying spin configurations. Because of these treatments, QS$^{3}$ can support large-scale quantum systems containing more than 1000 sites with dilute $N_{\downarrow}$. We show the benchmark results of QS$^{3}$ for the low-energy excitation dispersion of the isotropic Heisenberg model on the $10\times10\times10$ cubic lattice, the static and dynamical spin structure factors of the isotropic Heisenberg model on the $10\times10$ square lattice, and the open-MP parallelization efficiency on the supercomputer (Ohtaka) based on AMD Epyc 7702 installed at the Institute for the Solid State Physics (ISSP). Theoretical backgrounds and the user interface of QS$^{3}$ are also described.

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