Robust Analytic-Continuation Approach to Many-Body <i>GW</i> Calculations

Duchemin, Ivan; Blase, Xavier

doi:10.1021/acs.jctc.9b01235

Cited by 70 publications

(107 citation statements)

References 84 publications

(173 reference statements)

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“…The AC scheme has been shown to give accurate G 0 W 0 valence state energies in molecules and solids [21,34,54]. However, analytic continuation is known to be very unstable for states far away from the Fermi level (e.g., core excitation energies) and thus gives inaccurate G 0 W 0 QP energies for those states [55]. A more robust scheme is the contour deformation (CD) approach [13,37], where the integral over the real frequency axis in Eq.…”

Section: Contour Deformationmentioning

confidence: 99%

All-Electron Gaussian-Based G₀W₀ for Valence and Core Excitation Energies of Periodic Systems

Zhu

Chan

2021

J. Chem. Theory Comput.

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We describe an all-electron G 0 W 0 implementation for periodic systems with-point sampling implemented in a crystalline Gaussian basis. Our full-frequency G 0 W 0 method relies on efficient Gaussian density fitting integrals and includes both analytic continuation and contour deformation schemes. Due to the compactness of Gaussian bases, no virtual state truncation is required as is seen in many plane-wave formulations. Finite size corrections are included by taking the → limit of the Coulomb divergence. Using our implementation, we study quasiparticle energies and band structures across a range of systems including molecules, semiconductors, rare gas solids, and metals. We find that the G 0 W 0 band gaps of traditional semiconductors converge rapidly with respect to the basis size, even for the conventionally challenging case of ZnO. Using correlation-consistent bases of polarized triple-zeta quality, we find the mean absolute relative error of the extrapolated G 0 W 0 @PBE band gaps to be only 5.2% when compared to experimental values. For core excitation binding energies (CEBEs), we find that G 0 W 0 predictions improve significantly over those from DFT if the G 0 W 0 calculations are started from hybrid functionals with a high percentage of exact exchange.

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Section: Contour Deformationmentioning

confidence: 99%

All-Electron Gaussian-Based G₀W₀ for Valence and Core Excitation Energies of Periodic Systems

Zhu

Chan

2021

J. Chem. Theory Comput.

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“…However, we also observe that, in some cases, unphysical irregularities on the ground-state PES, which are due to the appearance of a satellite resonance with a weight similar to that of the GW quasiparticle peak. [78][79][80][81][82] In order to compute the neutral (optical) excitations of the system and their associated oscillator strengths, the BSE expresses the two-body propagator 4,83 L(1, 2, 1 , 2 ) = L 0 (1, 2, 1 , 2 )…”

mentioning

confidence: 99%

“…This shortcoming has been thoroughly described in several previous studies. [78][79][80][81][82] We believe that this central issue must be resolved if one wants to expand the applicability of the present method.…”

mentioning

confidence: 99%

Pros and Cons of the Bethe–Salpeter Formalism for Ground-State Energies

Loos

Scemama

Duchemin

et al. 2020

J. Phys. Chem. Lett.

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The combination of the many-body Green's function GW approximation and the Bethe-Salpeter equation (BSE) formalism has shown to be a promising alternative to time-dependent density-functional theory (TD-DFT) for computing vertical transition energies and oscillator strengths in molecular systems. The BSE formalism can also be employed to compute ground-state correlation energies thanks to the adiabatic-connection fluctuationdissipation theorem (ACFDT). Here, we study the topology of the ground-state potential energy surfaces (PES) of several diatomic molecules near their equilibrium bond length. Thanks to comparisons with state-of-art computational approaches (CC3), we show that ACFDT@BSE is surprisingly accurate, and can even compete with lower-order coupled cluster methods (CC2 and CCSD) in terms of total energies and equilibrium bond distances for the considered systems. However, we sometimes observe unphysical irregularities on the groundstate PES in relation with difficulties in the identification of a few GW quasiparticle energies.

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“…The self-energy is first calculated for a set of imaginary frequencies iω and then continued to the real-frequency axis by fitting the matrix elements �ðiωÞ to a multipole model (either the so-called 2-polemodel [84,85] or the Padé approximant [86][87][88]). A fully-analytical approach (FAA) [89][90][91][92] can be used to perform the integration in Eq. (21) .…”

Section: Gw Approximationmentioning

confidence: 99%

Ab initio modeling of excitons: from perfect crystals to biomaterials

Tirimbó

Baumeier

2021

Advances in Physics: X

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Excitons, or coupled electron-hole excitations, are important both for fundamental optical properties of materials as well as and for the functionality of materials in opto-electronic devices. Depending on the material they are created in, excitons can come in many forms, from Wannier-Mott excitons in inorganic semiconductors, to molecular Frenkel or bi-molecular chargetransfer excitons in disordered organic or biological heterostructures. This multitude of materials and exciton types poses tremendous challenges for ab initio modeling. Following a brief overview of typical ab initio techniques, we summarize our recent work based on Many-Body Green's Functions Theory in the GW approximation and Bethe-Salpeter Equation (BSE) as a method applicable to a wide range of material classes from perfect crystals to disordered materials. In particular, we emphasize the current challenges of embedding this GW-BSE method into multi-method, mixed quantum-classical (QM/MM) models for organic materials and illustrate them with examples from organic photovoltaics and fluorescence spectroscopy. Our perspectives on future studies are also presented.

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Robust Analytic-Continuation Approach to Many-Body GW Calculations

Cited by 70 publications

References 84 publications

All-Electron Gaussian-Based G₀W₀ for Valence and Core Excitation Energies of Periodic Systems

All-Electron Gaussian-Based G₀W₀ for Valence and Core Excitation Energies of Periodic Systems

Pros and Cons of the Bethe–Salpeter Formalism for Ground-State Energies

Ab initio modeling of excitons: from perfect crystals to biomaterials

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Robust Analytic-Continuation Approach to Many-Body GW Calculations

Cited by 70 publications

References 84 publications

All-Electron Gaussian-Based G0W0 for Valence and Core Excitation Energies of Periodic Systems

All-Electron Gaussian-Based G0W0 for Valence and Core Excitation Energies of Periodic Systems

Pros and Cons of the Bethe–Salpeter Formalism for Ground-State Energies

Ab initio modeling of excitons: from perfect crystals to biomaterials

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Product

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All-Electron Gaussian-Based G₀W₀ for Valence and Core Excitation Energies of Periodic Systems

All-Electron Gaussian-Based G₀W₀ for Valence and Core Excitation Energies of Periodic Systems