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Anand N, Barry K, Neu JN, Graf DE, Huang Q, Zhou H, Siegrist T, Changlani HJ, Beekman C. Investigation of the monopole magneto-chemical potential in spin ices using capacitive torque magnetometry. Nat Commun 2022; 13:3818. [PMID: 35780148 PMCID: PMC9250528 DOI: 10.1038/s41467-022-31297-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 06/10/2022] [Indexed: 11/20/2022] Open
Abstract
The single-ion anisotropy and magnetic interactions in spin-ice systems give rise to unusual non-collinear spin textures, such as Pauling states and magnetic monopoles. The effective spin correlation strength (Jeff) determines the relative energies of the different spin-ice states. With this work, we display the capability of capacitive torque magnetometry in characterizing the magneto-chemical potential associated with monopole formation. We build a magnetic phase diagram of Ho2Ti2O7, and show that the magneto-chemical potential depends on the spin sublattice (α or β), i.e., the Pauling state, involved in the transition. Monte Carlo simulations using the dipolar-spin-ice Hamiltonian support our findings of a sublattice-dependent magneto-chemical potential, but the model underestimates the Jeff for the β-sublattice. Additional simulations, including next-nearest neighbor interactions (J2), show that long-range exchange terms in the Hamiltonian are needed to describe the measurements. This demonstrates that torque magnetometry provides a sensitive test for Jeff and the spin-spin interactions that contribute to it. Magnetic-field induced phase transitions in spin-ice materials have been investigated with various experimental techniques. Here, the authors demonstrate the capability of capacitive torque magnetometry in probing magnetic interaction energies and establishing magnetic phase boundaries in Ho2Ti2O7.
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Affiliation(s)
- Naween Anand
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA.,Intel Corp., Hillsboro, OR, 97124, USA
| | - Kevin Barry
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA.,Florida State University, Department of Physics, Tallahassee, FL, 32306, USA.,Ateios Systems, Newberry, IN, 47449, USA
| | - Jennifer N Neu
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA.,Florida State University, Department of Physics, Tallahassee, FL, 32306, USA.,Oak Ridge National Laboratory, Nuclear Nonproliferation Division, Oak Ridge, TN, 37831, USA
| | - David E Graf
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - Qing Huang
- University of Tennessee, Department of Physics, Knoxville, TN, 37996, USA
| | - Haidong Zhou
- University of Tennessee, Department of Physics, Knoxville, TN, 37996, USA
| | - Theo Siegrist
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA.,Florida Agricultural and Mechanical University and Florida State University, College of Engineering, Tallahassee, FL, 32310, USA
| | - Hitesh J Changlani
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA.,Florida State University, Department of Physics, Tallahassee, FL, 32306, USA
| | - Christianne Beekman
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA. .,Florida State University, Department of Physics, Tallahassee, FL, 32306, USA.
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Paul A, Chung CM, Birol T, Changlani HJ. Paul et al. Reply. Phys Rev Lett 2021; 127:049702. [PMID: 34355961 DOI: 10.1103/physrevlett.127.049702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 06/16/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Arpita Paul
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Chia-Min Chung
- Department of Physics and Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universitat Munchen, Theresienstrasse 37, 80333 Munchen, Germany
| | - Turan Birol
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Hitesh J Changlani
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
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Paul A, Chung CM, Birol T, Changlani HJ. Spin-lattice Coupling and the Emergence of the Trimerized Phase in the S=1 Kagome Antiferromagnet Na_{2}Ti_{3}Cl_{8}. Phys Rev Lett 2020; 124:167203. [PMID: 32383953 DOI: 10.1103/physrevlett.124.167203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 03/13/2020] [Indexed: 06/11/2023]
Abstract
Spin-1 antiferromagnets are abundant in nature, but few theories exist to understand their properties and behavior when geometric frustration is present. Here we study the S=1 kagome compound Na_{2}Ti_{3}Cl_{8} using a combination of density functional theory, exact diagonalization, and density matrix renormalization group approaches to achieve a first principles supported explanation of its exotic magnetic phases. We find that the effective magnetic Hamiltonian includes essential non-Heisenberg terms that do not stem from spin-orbit coupling, and both trimerized and spin-nematic magnetic phases are relevant. The experimentally observed structural transition to a breathing kagome phase is driven by spin-lattice coupling, which favors the trimerized magnetic phase against the quadrupolar one. We thus show that lattice effects can be necessary to understand the magnetism in frustrated magnetic compounds and surmise that Na_{2}Ti_{3}Cl_{8} is a compound that cannot be understood from only electronic or only lattice Hamiltonians, very much like VO_{2}.
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Affiliation(s)
- Arpita Paul
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Chia-Min Chung
- Department of Physics and Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universitat Munchen, Theresienstrasse 37, 80333 Munchen, Germany
| | - Turan Birol
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Hitesh J Changlani
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
- National High Magnetic Field Laboratory, Tallahassee, Florida 32304, USA
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Chauhan P, Mahmood F, Changlani HJ, Koohpayeh SM, Armitage NP. Tunable Magnon Interactions in a Ferromagnetic Spin-1 Chain. Phys Rev Lett 2020; 124:037203. [PMID: 32031844 DOI: 10.1103/physrevlett.124.037203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 10/07/2019] [Indexed: 06/10/2023]
Abstract
NiNb_{2}O_{6} is an almost ideal realization of a 1D spin-1 ferromagnetic Heisenberg chain compound with weak unidirectional anisotropy. Using time-domain THz spectroscopy, we measure the low-energy electrodynamic response of NiNb_{2}O_{6} as a function of temperature and external magnetic field. At low temperatures, we find a magnonlike spin excitation, which corresponds to the lowest energy excitation at q∼0. At higher temperatures, we unexpectedly observe a temperature-dependent renormalization of the spin-excitation energy, which has a strong dependence on field direction. Using theoretical arguments, exact diagonalizations, and finite temperature dynamical Lanczos calculations, we construct a picture of magnon-magnon interactions that naturally explains the observed renormalization. We show how magnetic field strength and direction may be used to directly tune the sign of the magnon-magnon interaction. This unique scenario is a consequence of the spin-1 nature and has no analog in the more widely studied spin-1/2 systems.
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Affiliation(s)
- Prashant Chauhan
- The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Fahad Mahmood
- The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Hitesh J Changlani
- The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
- National High Magnetic Field Laboratory, Tallahassee, Florida 32304, USA
| | - S M Koohpayeh
- The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - N P Armitage
- The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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Zhang S, Changlani HJ, Plumb KW, Tchernyshyov O, Moessner R. Dynamical Structure Factor of the Three-Dimensional Quantum Spin Liquid Candidate NaCaNi_{2}F_{7}. Phys Rev Lett 2019; 122:167203. [PMID: 31075014 DOI: 10.1103/physrevlett.122.167203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Indexed: 06/09/2023]
Abstract
We study the dynamical structure factor of the spin-1 pyrochlore material NaCaNi_{2}F_{7}, which is well described by a weakly perturbed nearest-neighbour Heisenberg Hamiltonian, Our three approaches-molecular dynamics simulations, stochastic dynamical theory, and linear spin wave theory-reproduce remarkably well the momentum dependence of the experimental inelastic neutron scattering intensity as well as its energy dependence with the exception of the lowest energies. We discuss two surprising aspects and their implications for quantum spin liquids in general: the complete lack of sharp quasiparticle excitations in momentum space and the success of the linear spin wave theory in a regime where it would be expected to fail for several reasons.
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Affiliation(s)
- Shu Zhang
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Hitesh J Changlani
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
- National High Magnetic Field Laboratory, Tallahassee, Florida 32304, USA
| | - Kemp W Plumb
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
| | - Oleg Tchernyshyov
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Roderich Moessner
- Max-Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
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Changlani HJ, Kochkov D, Kumar K, Clark BK, Fradkin E. Macroscopically Degenerate Exactly Solvable Point in the Spin-1/2 Kagome Quantum Antiferromagnet. Phys Rev Lett 2018; 120:117202. [PMID: 29601762 DOI: 10.1103/physrevlett.120.117202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Indexed: 06/08/2023]
Abstract
Frustrated quantum magnets are a central theme in condensed matter physics due to the richness of their phase diagrams. They support a panoply of phases including various ordered states and topological phases. Yet, this problem has defied a solution for a long time due to the lack of controlled approximations which make it difficult to distinguish between competing phases. Here we report the discovery of a special quantum macroscopically degenerate point in the XXZ model on the spin-1/2 kagome quantum antiferromagnet for the ratio of Ising to antiferromagnetic transverse coupling J_{z}/J=-1/2. This point is proximate to many competing phases explaining the source of the complexity of the phase diagram. We identify five phases near this point including both spin-liquid and broken-symmetry phases and give evidence that the kagome Heisenberg antiferromagnet is close to a transition between two phases.
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Affiliation(s)
- Hitesh J Changlani
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana Illinois 61801, USA
| | - Dmitrii Kochkov
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana Illinois 61801, USA
| | - Krishna Kumar
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana Illinois 61801, USA
| | - Bryan K Clark
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana Illinois 61801, USA
| | - Eduardo Fradkin
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana Illinois 61801, USA
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Scheie A, Kindervater J, Säubert S, Duvinage C, Pfleiderer C, Changlani HJ, Zhang S, Harriger L, Arpino K, Koohpayeh SM, Tchernyshyov O, Broholm C. Reentrant Phase Diagram of Yb_{2}Ti_{2}O_{7} in a ⟨111⟩ Magnetic Field. Phys Rev Lett 2017; 119:127201. [PMID: 29341662 DOI: 10.1103/physrevlett.119.127201] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Indexed: 06/07/2023]
Abstract
We present a magnetic phase diagram of rare-earth pyrochlore Yb_{2}Ti_{2}O_{7} in a ⟨111⟩ magnetic field. Using heat capacity, magnetization, and neutron scattering data, we show an unusual field dependence of a first-order phase boundary, wherein a small applied field increases the ordering temperature. The zero-field ground state has ferromagnetic domains, while the spins polarize along ⟨111⟩ above 0.65 T. A classical Monte Carlo analysis of published Hamiltonians does account for the critical field in the low T limit. However, this analysis fails to account for the large bulge in the reentrant phase diagram, suggesting that either long-range interactions or quantum fluctuations govern low field properties.
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Affiliation(s)
- A Scheie
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - J Kindervater
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - S Säubert
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
- Heinz Maier-Leibnitz Zentrum, Technische Universität München, D-85748 Garching, Germany
| | - C Duvinage
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - C Pfleiderer
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - H J Changlani
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - S Zhang
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - L Harriger
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - K Arpino
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - S M Koohpayeh
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - O Tchernyshyov
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - C Broholm
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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Affiliation(s)
- Adam A. Holmes
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, United States
| | - Hitesh J. Changlani
- Department of Physics, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - C. J. Umrigar
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, United States
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Changlani HJ, Zheng H, Wagner LK. Erratum: "Density-matrix based determination of low-energy model Hamiltonians from ab initio wavefunctions" [J. Chem. Phys. 143, 102814 (2015)]. J Chem Phys 2015; 143:189901. [PMID: 26567690 DOI: 10.1063/1.4935702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Hitesh J Changlani
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green St., Urbana, Illinois 61801, USA
| | - Huihuo Zheng
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green St., Urbana, Illinois 61801, USA
| | - Lucas K Wagner
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green St., Urbana, Illinois 61801, USA
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Changlani HJ, Zheng H, Wagner LK. Density-matrix based determination of low-energy model Hamiltonians from ab initio wavefunctions. J Chem Phys 2015; 143:102814. [PMID: 26374007 DOI: 10.1063/1.4927664] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Hitesh J. Changlani
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green St., Urbana, Illinois 61801, USA
| | - Huihuo Zheng
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green St., Urbana, Illinois 61801, USA
| | - Lucas K. Wagner
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green St., Urbana, Illinois 61801, USA
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Changlani HJ, Ghosh S, Pujari S, Henley CL. Emergent spin excitations in a Bethe lattice at percolation. Phys Rev Lett 2013; 111:157201. [PMID: 24160622 DOI: 10.1103/physrevlett.111.157201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Indexed: 06/02/2023]
Abstract
We study the spin-1/2 quantum Heisenberg antiferromagnet on a Bethe lattice diluted to the percolation threshold. Dilution creates areas of even or odd sublattice imbalance resulting in "dangling spins" [L. Wang and A. W. Sandvik, Phys. Rev. Lett. 97, 117204 (2006); Phys. Rev. B 81, 054417 (2010)]. These collectively act as "emergent" spin-1/2 degrees of freedom and are responsible for the creation of a set of low-lying "quasidegenerate states." Using density matrix renormalization group calculations, we detect the presence and location of these emergent spins. We find an effective Hamiltonian of these emergent spins, with Heisenberg interactions that decay exponentially with the distance between them.
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Affiliation(s)
- Hitesh J Changlani
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
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Petruzielo FR, Holmes AA, Changlani HJ, Nightingale MP, Umrigar CJ. Semistochastic projector Monte Carlo method. Phys Rev Lett 2012; 109:230201. [PMID: 23368167 DOI: 10.1103/physrevlett.109.230201] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Indexed: 06/01/2023]
Abstract
We introduce a semistochastic implementation of the power method to compute, for very large matrices, the dominant eigenvalue and expectation values involving the corresponding eigenvector. The method is semistochastic in that the matrix multiplication is partially implemented numerically exactly and partially stochastically with respect to expectation values only. Compared to a fully stochastic method, the semistochastic approach significantly reduces the computational time required to obtain the eigenvalue to a specified statistical uncertainty. This is demonstrated by the application of the semistochastic quantum Monte Carlo method to systems with a sign problem: the fermion Hubbard model and the carbon dimer.
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Affiliation(s)
- F R Petruzielo
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.
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