Many-body correlations and coupling in benzene-dithiol junctions

Rangel, Tonatiuh; Ferretti, Andrea; Olevano, Valério; Rignanese, Gian‐Marco

doi:10.1103/physrevb.95.115137

Cited by 6 publications

(7 citation statements)

References 74 publications

(108 reference statements)

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“…GW self-energy has been recognized as a good approach to correct for this error and to describe more accurately the energy level alignment at the molecule-metal interface. However, it has been shown that GW corrections affect rather unoccupied orbitals (poorly described within the ground state DFT) while occupied levels (in particular, the HOMO) are only slightly altered 48,49 . Since the charge transport in M1 and M6 is dominated by the HOMO level, we hope that our mean-field DFT studies are good enough to provide reliable comparative results.…”

Section: Resultsmentioning

confidence: 99%

Tuning spin filtering by anchoring groups in benzene derivative molecular junctions

Dappe

2019

J. Phys.: Condens. Matter

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One of the important issues of molecular spintronics is the control and manipulation of charge transport and, in particular, its spin polarization through single-molecule junctions. Using ab initio calculations, we explore spin-polarized electron transport across single benzene derivatives attached with six different anchoring groups (S, CH3S, COOH, CNH2NH, NC and NO2) to Ni(111) electrodes. We find that molecule-electrode coupling, conductance and spin polarization (SP) of electric current can be modified significantly by anchoring groups. In particular, a high spin polarization (SP > 80%) and a giant magnetoresistance (MR > 140%) can be achieved for NO2 terminations and, more interestingly, SP can be further enhanced (up to 90%) by a small voltage. The S and CH3S systems, on the contrary, exhibit rather low SP while intermediate values are found for COOH and CNH2NH groups. The results are analyzed in detail and explained by orbital symmetry arguments, hybridization and spatial localization of frontier molecular orbitals. We hope that our comparative and systematic studies will provide valuable quantitative information for future experimental measurements on that kind of systems and will be useful for designing high-performance spintronics devices.

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Section: Resultsmentioning

confidence: 99%

Tuning spin filtering by anchoring groups in benzene derivative molecular junctions

Dappe

2019

J. Phys.: Condens. Matter

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“…In DFT+Σ, we introduce a separate self-energy Σ in the subspace of the central region Hamiltonian H to correct the KS eigenvalues for missing exchange and correlation effects (the Σ in DFT+Σ). While prior work has performed a more rigorous GW calculation on molecular junctions to evaluate Σ, ,, such an approach is not yet feasible for many increasingly complex systems of interest. Instead, here we work within the DFT+Σ framework described above, generalizing it to covalently bound junctions.…”

Section: Methodsmentioning

confidence: 99%

First-Principles Approach to the Conductance of Covalently Bound Molecular Junctions

et al. 2019

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We develop a first-principles approach for accurate conductance calculations of covalently bound molecular junctions. Our approach extends the DFT+Σ method, an approximate GW-based self-energy correction scheme acting on a tractable molecular subspace (based on a gas-phase reference of the same dimension) that corrects level alignment in the junction relative to density functional theory (DFT). We introduce a new extended gas-phase reference system, consisting of the molecule and several lead atoms, whose frontier orbitals maximally project onto the conducting orbitals of the junction. With this choice of reference, our self-energy correction to the Kohn–Sham Hamiltonian takes into account mixing of the gas-phase reference orbitals upon the formation of the junction. We apply our generalized DFT+Σ approach to a series of alkane–chain junctions in which the molecules are covalently bound to the leads via carboxyl terminal groups. Our results lead to conductance values in quantitative agreement with experiment. We also revisit the well-studied Au–bipyridine–Au junction and show that we recover the original DFT+Σ approach for relatively weak donor–acceptor molecule–lead binding.

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“…The approach used in this work is still based on the Landauer formalism, but with a corrected electronic structure. Along these lines several authors have already attempted to go beyond DFT+Landauer to describe quantum transport in molecular junctions, for example by using semi-empirical models like the image-charge DFT+Σ model 17 , or fully ab initio approaches 22,23 like GW or COHSEX. Such attempts remain rare in the literature.…”

Section: Introductionmentioning

confidence: 99%

Plane-wave many-body corrections to the conductance in bulk tunnel junctions

et al. 2020

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The conductance of bulk metal-insulator-metal junctions is evaluated by the Landauer formula using an ab initio electronic structure calculated using a plane-waves basis set within density-functional theory (DFT) and beyond, i.e. including exact non-local exchange using hybrid functional (HSE) or many-body G0W0 and COHSEX quasiparticle (QP) schemes. We consider an Ag/MgO/Ag heterostructure model and we focus on the evolution of the zero-bias conductance as a function of the MgO film thickness. Our study shows that the correction of the electronic structure beyond semi-local density functionals goes in the right direction to improve the agreement with experiments, significantly reducing the zero-bias conductance. This effect becomes more evident at larger MgO thickness, that is in increasing tunneling regime. We also observe that the reduction of the conductance seems more related to the correction of wavefunctions rather than energies, and thus not directly related to the correction of the band-gap of bulk MgO. G0W0 and HSE both provide a correct band-gap in agreement with experiments, but only HSE gives a significant reduction of the conductance. COHSEX, while overestimating the band-gap, gives a reduction of the conductance very close to HSE. arXiv:1910.02761v1 [cond-mat.mes-hall]

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Many-body correlations and coupling in benzene-dithiol junctions

Cited by 6 publications

References 74 publications

Tuning spin filtering by anchoring groups in benzene derivative molecular junctions

Tuning spin filtering by anchoring groups in benzene derivative molecular junctions

First-Principles Approach to the Conductance of Covalently Bound Molecular Junctions

Plane-wave many-body corrections to the conductance in bulk tunnel junctions

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