{"paper":{"title":"Critical level crossings and gapless spin liquid in the square-lattice spin-$1/2$ $J_1$-$J_2$ Heisenberg antiferromagnet","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["cond-mat.stat-mech"],"primary_cat":"cond-mat.str-el","authors_text":"Anders W. Sandvik, Ling Wang","submitted_at":"2017-02-27T09:07:12Z","abstract_excerpt":"We use the DMRG method to calculate several energy eigenvalues of the frustrated $S=1/2$ square-lattice $J_1$-$J_2$ Heisenberg model on $2L \\times L$ cylinders with $L \\le 10$. We identify excited-level crossings versus the coupling ratio $g=J_2/J_1$ and study their drifts with the system size $L$. The lowest singlet-triplet and singlet-quintuplet crossings converge rapidly (with corrections $\\propto L^{-2}$) to different $g$ values, and we argue that these correspond to ground-state transitions between the N\\'eel antiferromagnet and a gapless spin liquid, at $g_{c1} \\approx 0.46$, and between"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1702.08197","kind":"arxiv","version":4},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}