Maximally localized Wannier functions in LaMnO3within PBE +U, hybrid functionals and partially self-consistent GW: an efficient route to constructab initiotight-binding parameters for egperovskites

Franchini, Cesare; Kováčik, Roman; Marsman, Martijn; Murthy, Sowmya Sathyanarayana; He, Jiangang; Ederer, Claude; Kresse, Georg

doi:10.1088/0953-8984/24/23/235602

Cited by 136 publications

(141 citation statements)

References 91 publications

(246 reference statements)

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“…The energy cutoff for the response function was set to 150 eV. We made use of the VASP2WANNIER90 interface to interpolate the band structures to a finer grid 53,54 . The search of the centric structure, as well as the symmetry analysis, was performed using the PSEUDO and AMPLIMODES tools on the Bilbao Crystallographic Server 55,56 .…”

Section: Methodsmentioning

confidence: 99%

Tunable ferroelectric polarization and its interplay with spin–orbit coupling in tin iodide perovskites

et al. 2014

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Ferroelectricity is a potentially crucial issue in halide perovskites, breakthrough materials in photovoltaic research. Using density functional theory simulations and symmetry analysis, we show that the lead-free perovskite iodide (FA)SnI 3 , containing the planar formamidinium cation FA, (NH 2 CHNH 2 ) þ , is ferroelectric. In fact, the perpendicular arrangement of FA planes, leading to a 'weak' polarization, is energetically more stable than parallel arrangements of FA planes, being either antiferroelectric or 'strong' ferroelectric. Moreover, we show that the 'weak' and 'strong' ferroelectric states with the polar axis along different crystallographic directions are energetically competing. Therefore, at least at low temperatures, an electric field could stabilize different states with the polarization rotated by p/4, resulting in a highly tunable ferroelectricity appealing for multistate logic. Intriguingly, the relatively strong spin-orbit coupling in noncentrosymmetric (FA)SnI 3 gives rise to a co-existence of Rashba and Dresselhaus effects and to a spin texture that can be induced, tuned and switched by an electric field controlling the ferroelectric state.

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Section: Methodsmentioning

confidence: 99%

Tunable ferroelectric polarization and its interplay with spin–orbit coupling in tin iodide perovskites

et al. 2014

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“…To this aim the Kohn Sham orbitals were projected on to maximally localized Wannier functions 34 using the Wannier90 code. 35,36 For the construction of the correlated subspace we have followed the hybrid "d-dp Hamiltonian"-like approach suggested by Vaugier and coworkers…”

Section: Methodsmentioning

confidence: 99%

Coexistence of trapped and free excess electrons inSrTiO3

et al. 2015

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The question whether excess electrons in SrTiO3 form free or trapped carriers is a crucial aspect for the electronic properties of this important material. This fundamental ambiguity prevents a consistent interpretation of the puzzling experimental situation, where results support one or the other scenario depending on the type of experiment that is conducted. Using density functional theory with an on-site Coulomb interaction U, we show that excess electrons form small polarons if the density of electronic carriers is higher than ≈ 10 20 cm −3 . Below this value, the electrons stay delocalized or become large polarons. For oxygen-deficient SrTiO3, small polarons confined to Ti 3+ sites are immobile at low temperature but can be thermally activated into a conductive state, which explains the metal-insulator transition observed experimentally.

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“…We interpolate the band structure to a finer grid using the WANNIER90 code [154] and the VASP2-WANNIER90 interface [155]. With respect to GW calculations, it is important to mention that (i) solely including valence electrons leads to an erroneous wave-vector dependence of the GW correction [145], (ii) the convergence with respect to virtual states when calculating W is particularly slow for 1L-MoS 2 [156], and (iii) the default value for the number of quasiparticle energies that are calculated and updated in the scGW VASP calculation must be substantially increased.…”

Section: Electronic Structurementioning

confidence: 99%

Vibrational and optical properties of MoS2: From monolayer to bulk

Molina-Sánchez

Hummer

Wirtz

2015

Surface Science Reports

213

167

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Molybdenum disulfide, MoS 2 , has recently gained considerable attention as a layered material where neighboring layers are only weakly interacting and can easily slide against each other. Therefore, mechanical exfoliation allows the fabrication of single and multi-layers and opens the possibility to generate atomically thin crystals with outstanding properties. In contrast to graphene, it has an optical gap of 1.9 eV. This makes it a prominent candidate for transistor and opto-electronic applications. Single-layer MoS 2 exhibits remarkably different physical properties compared to bulk MoS 2 due to the absence of interlayer hybridization. For instance, while the band gap of bulk and multi-layer MoS 2 is indirect, it becomes direct with decreasing number of layers. In this review, we analyze from a theoretical point of view the electronic, optical, and vibrational properties of single-layer, few-layer and bulk MoS 2 . In particular, we focus on the effects of spinorbit interaction, number of layers, and applied tensile strain on the vibrational and optical properties. We examine the results obtained by different methodologies, mainly ab initio approaches. We also discuss which approximations are suitable for MoS 2 and layered materials. The effect of external strain on the band gap of single-layer MoS 2 and the crossover from indirect to direct band gap is investigated. We analyze the excitonic effects on the absorption spectra. The main features, such as the double peak at the absorption threshold and the high-energy exciton are presented. Furthermore, we report on the phonon dispersion relations of single-layer, few-layer and bulk MoS 2 . Based on the latter, we explain the behavior of the Raman-active A 1g and E 1 2g modes as a function of the number of layers. Finally, we compare theoretical and experimental results of Raman, photoluminescence, and optical-absorption spectroscopy.

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Maximally localized Wannier functions in LaMnO₃within PBE +U, hybrid functionals and partially self-consistent GW: an efficient route to constructab initiotight-binding parameters for e_gperovskites

Cited by 136 publications

References 91 publications

Tunable ferroelectric polarization and its interplay with spin–orbit coupling in tin iodide perovskites

Tunable ferroelectric polarization and its interplay with spin–orbit coupling in tin iodide perovskites

Coexistence of trapped and free excess electrons inSrTiO3

Vibrational and optical properties of MoS2: From monolayer to bulk

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