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Open accessJournal ArticleDOI: 10.1063/5.0038748

Cavity-modulated ionization potentials and electron affinities from quantum electrodynamics coupled-cluster theory.

02 Mar 2021-Journal of Chemical Physics (AIP Publishing)-Vol. 154, Iss: 9, pp 094112-094112
Abstract: Quantum electrodynamics coupled-cluster (QED-CC) theory is used to model vacuum-field-induced changes to ground-state properties of a series of sodium halide compounds (NaX, X = F, Cl, Br, and I) strongly coupled to an optical cavity. Ionization potentials (IPs) and electron affinities (EAs) are presented, and it is demonstrated that EAs are easily modulated by cavity interactions, while IPs for these compounds are far less sensitive to the presence of the cavity. EAs predicted by QED-CC can be reduced by as much as 0.22 eV (or ≈50%) when considering experimentally accessible coupling parameters.

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Topics: Ionization (54%), Coupled cluster (53%), Optical cavity (51%)
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5 results found


Journal ArticleDOI: 10.1021/ACS.JPCLETT.1C02659
Abstract: In the field of polaritonic chemistry, strong light-matter interactions are used to alter chemical reactions inside optical cavities. To understand these processes, the development of reliable theoretical models is essential. While traditional methods have to balance accuracy and system size, new developments in quantum computing offer a path for accurate calculations on currently available quantum devices. Here, we introduce the quantum electrodynamics unitary coupled cluster (QED-UCC) method combined with the Variational Quantum Eigensolver algorithm, as well as the quantum electrodynamics equation-of-motion (QED-EOM) method formulated in the qubit basis that allow accurate calculations of ground-state and excited-state properties of strongly coupled light-matter systems suitable for quantum computers. These methods show excellent agreement with the exact reference results and can outperform their traditional counterparts when strong electronic correlations become significant. This work sets the stage for future developments of polaritonic quantum chemistry methods suitable for both classical and quantum computers.

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Topics: Quantum computer (68%), Qubit (65%), Coupled cluster (56%) ... show more

5 Citations


Open accessPosted Content
Abstract: In the field of polaritonic chemistry, strong light-matter interactions are used to alter a chemical reaction inside an optical cavity. To explain and understand these processes, the development of reliable theoretical models is essential. While traditional methods have to balance accuracy and system size, new developments in quantum computing, in particular the Variational Quantum Eigensolver (VQE), offer a path for an accurate solution of the electronic Schrodinger equation with the promise of polynomial scaling and eventual quasi-exact solutions on currently available quantum devices. In this work, we combine these two fields. In particular, we introduce the quantum electrodynamics unitary coupled cluster (QED-UCC) method combined with the VQE algorithm, as well as the quantum electrodynamics equation-of-motion (QED-EOM) method formulated in the qubit basis that allows an accurate calculation of the ground-state and the excited-state properties of strongly coupled light-matter systems on a quantum computer. The accuracy and performance of the developed methods is tested for a H$_4$ molecule inside an optical cavity in a regime where strong electronic correlations become significant. For the first time, we explicitly include two photon effects from first principles. We show that the developed methods are in excellent agreement with the exact reference results and can outperform their traditional counterparts. The work presented here sets the stage for future developments of polaritonic quantum chemistry methods suitable for both classical and quantum computers.

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Topics: Quantum computer (66%), Qubit (64%), Coupled cluster (55%) ... show more

2 Citations


Open accessPosted Content
Abstract: Recent experimental advances in strongly coupled light-matter systems has sparked the development of general ab-initio methods capable of describing interacting light-matter systems from first principles. One of these methods, quantum-electrodynamical density-functional theory (QEDFT), promises computationally efficient calculations for large correlated light-matter systems with the quality of the calculation depending on the underlying approximation for the exchange-correlation functional. So far no true density-functional approximation has been introduced limiting the efficient application of the theory. In this paper, we introduce the first gradient-based density functional for the QEDFT exchange-correlation energy derived from the adiabatic-connection fluctuation-dissipation theorem. We benchmark this simple-to-implement approximation on small systems in optical cavities and demonstrate its relatively low computational costs for fullerene molecules up to C$_{180}$ coupled to 400,000 photon modes in a dissipative optical cavity. This work now makes first principle calculations of much larger systems possible within the QEDFT framework effectively combining quantum optics with large-scale electronic structure theory.

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1 Citations


Open accessJournal ArticleDOI: 10.1063/5.0057542
Abstract: Inspired by the formulation of quantum-electrodynamical time-dependent density functional theory (QED-TDDFT) by Rubio and coworkers, we propose an implementation that uses dimensionless amplitudes for describing the photonic contributions to QED-TDDFT electron-photon eigenstates. The leads to a symmetric QED-TDDFT coupling matrix, which is expected to facilitate the future development of analytic derivatives. Through a Gaussian atomic basis implementation of the QED-TDDFT method, we examined the effect of dipole self-energy, rotating wave approximation, and the Tamm-Dancoff approximation on the QED-TDDFT eigenstates of model compounds (ethene, formaldehyde, and benzaldehyde) in an optical cavity. We highlight, in the strong coupling regime, the role of higher-energy and off-resonance excited states with large transition dipole moments in the direction of the photonic field, which are automatically accounted for in our QED-TDDFT calculations and might substantially affect the energy and composition of polaritons associated with lower-energy electronic states.

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Topics: Dipole (54%), Time-dependent density functional theory (53%), Density functional theory (53%) ... show more

Open accessJournal ArticleDOI: 10.1063/5.0057542
Junjie Yang1, Qi Ou2, Zheng Pei3, Hua Wang1  +4 moreInstitutions (3)
Abstract: Inspired by the formulation of quantum-electrodynamical time-dependent density functional theory (QED-TDDFT) by Rubio and co-workers [Flick et al., ACS Photonics 6, 2757-2778 (2019)], we propose an implementation that uses dimensionless amplitudes for describing the photonic contributions to QED-TDDFT electron–photon eigenstates. This leads to a Hermitian QED-TDDFT coupling matrix that is expected to facilitate the future development of analytic derivatives. Through a Gaussian atomic basis implementation of the QED-TDDFT method, we examined the effect of dipole self-energy, rotating-wave approximation, and the Tamm–Dancoff approximation on the QED-TDDFT eigenstates of model compounds (ethene, formaldehyde, and benzaldehyde) in an optical cavity. We highlight, in the strong coupling regime, the role of higher-energy and off-resonance excited states with large transition dipole moments in the direction of the photonic field, which are automatically accounted for in our QED-TDDFT calculations and might substantially affect the energies and compositions of polaritons associated with lower-energy electronic states.

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Topics: Dipole (54%), Time-dependent density functional theory (53%), Density functional theory (53%) ... show more
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48 results found


Journal ArticleDOI: 10.1063/1.1727484
Abstract: A method is suggested for the calculation of the matrix elements of the logarithm of an operator which gives the exact wavefunction when operating on the wavefunction in the one‐electron approximation. The method is based on the use of the creation and annihilation operators, hole—particle formalism, Wick's theorem, and the technique of Feynman‐like diagrams. The connection of this method with the configuration‐interaction method as well as with the perturbation theory in the quantum‐field theoretical form is discussed. The method is applied to the simple models of nitrogen and benzene molecules. The results are compared with those obtained with the configuration‐interaction method considering all possible configurations within the chosen basis of one‐electron functions.

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Topics: Creation and annihilation operators (54%), Quantum field theory (53%), Intruder state (52%) ... show more

2,503 Citations


Journal ArticleDOI: 10.1103/REVMODPHYS.79.291
Rodney J. Bartlett1, Monika Musiał1Institutions (1)
Abstract: Today, coupled-cluster theory offers the most accurate results among the practical ab initio electronic-structure theories applicable to moderate-sized molecules. Though it was originally proposed for problems in physics, it has seen its greatest development in chemistry, enabling an extensive range of applications to molecular structure, excited states, properties, and all kinds of spectroscopy. In this review, the essential aspects of the theory are explained and illustrated with informative numerical results.

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2,287 Citations


Journal ArticleDOI: 10.1126/SCIENCE.1158722
08 Aug 2008-Science
Abstract: Density functional theory of electronic structure is widely and successfully applied in simulations throughout engineering and sciences. However, for many predicted properties, there are spectacular failures that can be traced to the delocalization error and static correlation error of commonly used approximations. These errors can be characterized and understood through the perspective of fractional charges and fractional spins introduced recently. Reducing these errors will open new frontiers for applications of density functional theory.

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1,852 Citations


Journal ArticleDOI: 10.1063/1.438728
Abstract: An approximate Xα functional is proposed from which the charge density fitting equations follow variationally. LCAO Xα calculations on atomic nickel and diatomic hydrogen show the method independent of the fitting (auxiliary) bases to within 0.02 eV. Variational properties associated with both orbital and auxiliary basis set incompleteness are used to approach within 0.2 eV the Xα total energy limit for the nitrogen molecule.

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1,152 Citations


Open accessJournal ArticleDOI: 10.1038/NATURE17974
Rohit Chikkaraddy1, Bart de Nijs1, Felix Benz1, Steven J. Barrow1  +6 moreInstitutions (3)
07 Jul 2016-Nature
Abstract: Photon emitters placed in an optical cavity experience an environment that changes how they are coupled to the surrounding light field. In the weak-coupling regime, the extraction of light from the emitter is enhanced. But more profound effects emerge when single-emitter strong coupling occurs: mixed states are produced that are part light, part matter1, 2, forming building blocks for quantum information systems and for ultralow-power switches and lasers. Such cavity quantum electrodynamics has until now been the preserve of low temperatures and complicated fabrication methods, compromising its use. Here, by scaling the cavity volume to less than 40 cubic nanometres and using host–guest chemistry to align one to ten protectively isolated methylene-blue molecules, we reach the strong-coupling regime at room temperature and in ambient conditions. Dispersion curves from more than 50 such plasmonic nanocavities display characteristic light–matter mixing, with Rabi frequencies of 300 millielectronvolts for ten methylene-blue molecules, decreasing to 90 millielectronvolts for single molecules—matching quantitative models. Statistical analysis of vibrational spectroscopy time series and dark-field scattering spectra provides evidence of single-molecule strong coupling. This dressing of molecules with light can modify photochemistry, opening up the exploration of complex natural processes such as photosynthesis and the possibility of manipulating chemical bonds.

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Topics: Cavity quantum electrodynamics (57%), Optical cavity (53%), Quantum optics (52%) ... show more

1,062 Citations


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20215