Large cumulant eigenvalue as a signature of exciton condensation

Schouten, Anna O.; Sager, LeeAnn M.; Mazziotti, David A.

doi:10.1103/physrevb.105.245151

Cited by 7 publications

(2 citation statements)

References 53 publications

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“…Li, Liebenthal, and DePrince 57 showed that the application of full 3POS improves the energetics for the 2‐ and 3‐dimensional H 10 structures, but errors on the order of 20–30 mE h were still observed. Aside from these model systems, Mazziotti and coworkers have applied v2RDM methods to a number of interesting systems, including conductive polymers, 98 nitrogonese cofactor, 99 cadmium telluride polymers, 100 and manganese porphyrin complexes 101 …”

Section: Numerical Applicationsmentioning

confidence: 99%

Variational determination of the two‐electron reduced density matrix: A tutorial review

Eugene DePrince

2024

WIREs Comput Mol Sci

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The two‐electron reduced density matrix (2RDM) carries enough information to evaluate the electronic energy of a many‐electron system. The variational 2RDM (v2RDM) approach seeks to determine the 2RDM directly, without knowledge of the wave function, by minimizing this energy with respect to variations in the elements of the 2RDM, while also enforcing known N‐representability conditions. In this tutorial review, we provide an overview of the theoretical underpinnings of the v2RDM approach and the N‐representability constraints that are typically applied to the 2RDM. We also discuss the semidefinite programming (SDP) techniques used in v2RDM computations and provide enough Python code to develop a working v2RDM code that interfaces to the libSDP library of SDP solvers.This article is categorized under: Electronic Structure Theory > Ab Initio Electronic Structure Methods Software > Quantum Chemistry

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Section: Numerical Applicationsmentioning

confidence: 99%

Variational determination of the two‐electron reduced density matrix: A tutorial review

Eugene DePrince

2024

WIREs Comput Mol Sci

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“…In several ways the EI is analogous to a superconductor, both being many-body phenomena beyond the scope of noninteracting electron theory and both involving the spontaneous emergence of a condensate. In the EI, the condensate is formed by excitons, bound states of electron–hole pairs ( 7 , 8 ). While this exotic instability is electronically driven in nature (i.e., triggered by the Coulomb interaction), it is in general accompanied by a structural phase transition with the same symmetry ( 9 ).…”

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confidence: 99%

The spontaneous symmetry breaking in Ta ₂ NiSe ₅ is structural in nature

Baldini

Zong

Choi

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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The excitonic insulator is an electronically driven phase of matter that emerges upon the spontaneous formation and Bose condensation of excitons. Detecting this exotic order in candidate materials is a subject of paramount importance, as the size of the excitonic gap in the band structure establishes the potential of this collective state for superfluid energy transport. However, the identification of this phase in real solids is hindered by the coexistence of a structural order parameter with the same symmetry as the excitonic order. Only a few materials are currently believed to host a dominant excitonic phase, Ta 2 NiSe 5 being the most promising. Here, we test this scenario by using an ultrashort laser pulse to quench the broken-symmetry phase of this transition metal chalcogenide. Tracking the dynamics of the material’s electronic and crystal structure after light excitation reveals spectroscopic fingerprints that are compatible only with a primary order parameter of phononic nature. We rationalize our findings through state-of-the-art calculations, confirming that the structural order accounts for most of the gap opening. Our results suggest that the spontaneous symmetry breaking in Ta 2 NiSe 5 is mostly of structural character, hampering the possibility to realize quasi-dissipationless energy transport.

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Quantum phase transitions in a model Hamiltonian exhibiting entangled simultaneous fermion-pair and exciton condensations

2022

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Large cumulant eigenvalue as a signature of exciton condensation

Cited by 7 publications

References 53 publications

Variational determination of the two‐electron reduced density matrix: A tutorial review

Variational determination of the two‐electron reduced density matrix: A tutorial review

The spontaneous symmetry breaking in Ta ₂ NiSe ₅ is structural in nature

Quantum phase transitions in a model Hamiltonian exhibiting entangled simultaneous fermion-pair and exciton condensations

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Large cumulant eigenvalue as a signature of exciton condensation

Cited by 7 publications

References 53 publications

Variational determination of the two‐electron reduced density matrix: A tutorial review

Variational determination of the two‐electron reduced density matrix: A tutorial review

The spontaneous symmetry breaking in Ta 2 NiSe 5 is structural in nature

Quantum phase transitions in a model Hamiltonian exhibiting entangled simultaneous fermion-pair and exciton condensations

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Product

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The spontaneous symmetry breaking in Ta ₂ NiSe ₅ is structural in nature