Efficient density matrix renormalization group algorithm to study Y junctions with integer and half-integer spin

Handle URI:
http://hdl.handle.net/10754/601364
Title:
Efficient density matrix renormalization group algorithm to study Y junctions with integer and half-integer spin
Authors:
Kumar, Manoranjan; Parvej, Aslam; Thomas, Simil ( 0000-0002-8069-4940 ) ; Ramasesha, S.; Soos, Z. G.
Abstract:
An efficient density matrix renormalization group (DMRG) algorithm is presented and applied to Y junctions, systems with three arms of n sites that meet at a central site. The accuracy is comparable to DMRG of chains. As in chains, new sites are always bonded to the most recently added sites and the superblock Hamiltonian contains only new or once renormalized operators. Junctions of up to N=3n+1≈500 sites are studied with antiferromagnetic (AF) Heisenberg exchange J between nearest-neighbor spins S or electron transfer t between nearest neighbors in half-filled Hubbard models. Exchange or electron transfer is exclusively between sites in two sublattices with NA≠NB. The ground state (GS) and spin densities ρr=⟨Szr⟩ at site r are quite different for junctions with S=1/2, 1, 3/2, and 2. The GS has finite total spin SG=2S(S) for even (odd) N and for MG=SG in the SG spin manifold, ρr>0(<0) at sites of the larger (smaller) sublattice. S=1/2 junctions have delocalized states and decreasing spin densities with increasing N. S=1 junctions have four localized Sz=1/2 states at the end of each arm and centered on the junction, consistent with localized states in S=1 chains with finite Haldane gap. The GS of S=3/2 or 2 junctions of up to 500 spins is a spin density wave with increased amplitude at the ends of arms or near the junction. Quantum fluctuations completely suppress AF order in S=1/2 or 1 junctions, as well as in half-filled Hubbard junctions, but reduce rather than suppress AF order in S=3/2 or 2 junctions.
KAUST Department:
Solar and Photovoltaic Engineering Research Center (SPERC)
Citation:
Efficient density matrix renormalization group algorithm to study Y junctions with integer and half-integer spin 2016, 93 (7) Physical Review B
Publisher:
American Physical Society (APS)
Journal:
Physical Review B
Issue Date:
3-Feb-2016
DOI:
10.1103/PhysRevB.93.075107
Type:
Article
ISSN:
2469-9950; 2469-9969
Sponsors:
M.K. thanks DST for support through Ramanujan Fellowship No. SR/S2/RJN-69/2012 and DST for funding computation facility through Grant No. SNB/MK/14-15/137. Z.G.S. thanks NSF for partial support of this work through the Princeton MRSEC (Grant No. DMR-0819860). S.R. thanks DST India for financial support.
Additional Links:
http://link.aps.org/doi/10.1103/PhysRevB.93.075107
Appears in Collections:
Articles; Solar and Photovoltaic Engineering Research Center (SPERC)

Full metadata record

DC FieldValue Language
dc.contributor.authorKumar, Manoranjanen
dc.contributor.authorParvej, Aslamen
dc.contributor.authorThomas, Similen
dc.contributor.authorRamasesha, S.en
dc.contributor.authorSoos, Z. G.en
dc.date.accessioned2016-03-15T14:03:34Zen
dc.date.available2016-03-15T14:03:34Zen
dc.date.issued2016-02-03en
dc.identifier.citationEfficient density matrix renormalization group algorithm to study Y junctions with integer and half-integer spin 2016, 93 (7) Physical Review Ben
dc.identifier.issn2469-9950en
dc.identifier.issn2469-9969en
dc.identifier.doi10.1103/PhysRevB.93.075107en
dc.identifier.urihttp://hdl.handle.net/10754/601364en
dc.description.abstractAn efficient density matrix renormalization group (DMRG) algorithm is presented and applied to Y junctions, systems with three arms of n sites that meet at a central site. The accuracy is comparable to DMRG of chains. As in chains, new sites are always bonded to the most recently added sites and the superblock Hamiltonian contains only new or once renormalized operators. Junctions of up to N=3n+1≈500 sites are studied with antiferromagnetic (AF) Heisenberg exchange J between nearest-neighbor spins S or electron transfer t between nearest neighbors in half-filled Hubbard models. Exchange or electron transfer is exclusively between sites in two sublattices with NA≠NB. The ground state (GS) and spin densities ρr=⟨Szr⟩ at site r are quite different for junctions with S=1/2, 1, 3/2, and 2. The GS has finite total spin SG=2S(S) for even (odd) N and for MG=SG in the SG spin manifold, ρr>0(<0) at sites of the larger (smaller) sublattice. S=1/2 junctions have delocalized states and decreasing spin densities with increasing N. S=1 junctions have four localized Sz=1/2 states at the end of each arm and centered on the junction, consistent with localized states in S=1 chains with finite Haldane gap. The GS of S=3/2 or 2 junctions of up to 500 spins is a spin density wave with increased amplitude at the ends of arms or near the junction. Quantum fluctuations completely suppress AF order in S=1/2 or 1 junctions, as well as in half-filled Hubbard junctions, but reduce rather than suppress AF order in S=3/2 or 2 junctions.en
dc.description.sponsorshipM.K. thanks DST for support through Ramanujan Fellowship No. SR/S2/RJN-69/2012 and DST for funding computation facility through Grant No. SNB/MK/14-15/137. Z.G.S. thanks NSF for partial support of this work through the Princeton MRSEC (Grant No. DMR-0819860). S.R. thanks DST India for financial support.en
dc.language.isoenen
dc.publisherAmerican Physical Society (APS)en
dc.relation.urlhttp://link.aps.org/doi/10.1103/PhysRevB.93.075107en
dc.rightsArchived with thanks to Physical Review Ben
dc.titleEfficient density matrix renormalization group algorithm to study Y junctions with integer and half-integer spinen
dc.typeArticleen
dc.contributor.departmentSolar and Photovoltaic Engineering Research Center (SPERC)en
dc.identifier.journalPhysical Review Ben
dc.eprint.versionPublisher's Version/PDFen
dc.contributor.institutionS. N. Bose National Centre for Basic Sciences, Calcutta, Calcutta 700098, Indiaen
dc.contributor.institutionSolid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, Indiaen
dc.contributor.institutionDepartment of Chemistry, Princeton University, Princeton, New Jersey 08544, USAen
dc.contributor.affiliationKing Abdullah University of Science and Technology (KAUST)en
kaust.authorThomas, Similen
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