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  1. Article: Modular implementation of the linear- and cubic-scaling orbital minimization methods in electronic structure codes using atomic orbitals.

    Lebedeva, Irina V / García, Alberto / Artacho, Emilio / Ordejón, Pablo

    Royal Society open science

    2023  Volume 10, Issue 4, Page(s) 230063

    Abstract: We present a code modularization approach to design efficient and massively parallel cubic- and linear-scaling solvers for electronic structure calculations using atomic orbitals. The modular implementation of the orbital minimization method, in which ... ...

    Abstract We present a code modularization approach to design efficient and massively parallel cubic- and linear-scaling solvers for electronic structure calculations using atomic orbitals. The modular implementation of the orbital minimization method, in which linear algebra and parallelization issues are handled via external libraries, is demonstrated in the SIESTA code. The distributed block compressed sparse row (DBCSR) and scalable linear algebra package (ScaLAPACK) libraries are used for algebraic operations with sparse and dense matrices, respectively. The MatrixSwitch and libOMM libraries, recently developed within the Electronic Structure Library, facilitate switching between different matrix formats and implement the energy minimization. We show results comparing the performance of several cubic-scaling algorithms, and also demonstrate the parallel performance of the linear-scaling solvers, and their supremacy over the cubic-scaling solvers for insulating systems with sizes of several hundreds of atoms.
    Language English
    Publishing date 2023-04-26
    Publishing country England
    Document type Journal Article
    ZDB-ID 2787755-3
    ISSN 2054-5703
    ISSN 2054-5703
    DOI 10.1098/rsos.230063
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  2. Book ; Online: Tuning the Topological Band Gap of Bismuthene with Silicon-based Substrate

    Wittemeier, Nils / Ordejón, Pablo / Zanolli, Zeila

    2022  

    Abstract: Some meta-stable polymorphs of bismuth monolayer (bismuthene) can host topologically nontrivial phases. However, it remains unclear if these polymorphs can become stable through interaction with a substrate, whether their topological properties are ... ...

    Abstract Some meta-stable polymorphs of bismuth monolayer (bismuthene) can host topologically nontrivial phases. However, it remains unclear if these polymorphs can become stable through interaction with a substrate, whether their topological properties are preserved, and how to design an optimal substrate to make the topological phase more robust. Using first-principles techniques we demonstrate that bismuthene polymorphs can become stable over silicon carbide (SiC), silicon (Si), silicon dioxide (SiO2) and that the proximity interaction in the heterostructures has a significant effect on the electronic structure of the monolayer, even when bonding is weak. We show that the van der Waals interactions and the breaking of the sublattice symmetry are the main factors driving changes in the electronic structure. Our work demonstrates that substrate interaction can strengthen the topological properties of bismuthene polymorphs and make them accessible for experimental investigation and technological applications.
    Keywords Condensed Matter - Materials Science ; Condensed Matter - Mesoscale and Nanoscale Physics
    Subject code 530
    Publishing date 2022-02-28
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article: Interference effects in one-dimensional moiré crystals

    Wittemeier, Nils / Verstraete, Matthieu J. / Ordejón, Pablo / Zanolli, Zeila

    Carbon. 2022 Jan., v. 186

    2022  

    Abstract: Interference effects in finite sections of one-dimensional moiré crystals are investigated using a Landauer-Büttiker formalism within the tight-binding approximation. We explain interlayer transport in double-wall carbon nanotubes and design a predictive ...

    Abstract Interference effects in finite sections of one-dimensional moiré crystals are investigated using a Landauer-Büttiker formalism within the tight-binding approximation. We explain interlayer transport in double-wall carbon nanotubes and design a predictive model. Wave function interference is visible at the mesoscale: in the strong coupling regime, as a periodic modulation of quantum conductance and emergent localized states; in the localized-insulating regime, as a suppression of interlayer transport, and oscillations of the density of states. These results could be exploited to design quantum electronic devices.
    Keywords carbon ; carbon nanotubes ; models
    Language English
    Dates of publication 2022-01
    Size p. 416-422.
    Publishing place Elsevier Ltd
    Document type Article
    ISSN 0008-6223
    DOI 10.1016/j.carbon.2021.10.028
    Database NAL-Catalogue (AGRICOLA)

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  4. Article ; Online: Magnetic properties of coordination clusters with {Mn

    Achilli, Simona / Besson, Claire / He, Xu / Ordejón, Pablo / Meyer, Carola / Zanolli, Zeila

    Physical chemistry chemical physics : PCCP

    2022  Volume 24, Issue 6, Page(s) 3780–3787

    Abstract: We present a joint experimental and theoretical characterization of the magnetic properties of coordination clusters with an antiferromagnetic core of four magnetic ions. Two different compounds are analyzed, with Co and Mn ions in the core. While both ... ...

    Abstract We present a joint experimental and theoretical characterization of the magnetic properties of coordination clusters with an antiferromagnetic core of four magnetic ions. Two different compounds are analyzed, with Co and Mn ions in the core. While both molecules are antiferromagnetic, they display different sensitivities to external magnetic field, according to the different atomic magnetic moments and strength of the intra-molecular magnetic couplings. In particular, the dependence of the magnetization
    Language English
    Publishing date 2022-02-09
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/d1cp03904k
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  5. Book ; Online: Modular implementation of the linear and cubic-scaling orbital minimization methods in electronic structure codes using atomic orbitals

    Lebedeva, Irina V. / Garcia, Alberto / Artacho, Emilio / Ordejon, Pablo

    2022  

    Abstract: We present a code modularization approach to design efficient and massively parallel cubic and linear-scaling solvers for electronic structure calculations using atomic orbitals. The modular implementation of the orbital minimization method, in which ... ...

    Abstract We present a code modularization approach to design efficient and massively parallel cubic and linear-scaling solvers for electronic structure calculations using atomic orbitals. The modular implementation of the orbital minimization method, in which linear algebra and parallelization issues are handled via external libraries, is demonstrated in the SIESTA code. The DBCSR and ScaLAPACK libraries are used for algebraic operations with sparse and dense matrices, respectively. The MatrixSwitch and libOMM libraries, recently developed within the Electronic Structure Library, facilitate switching between different matrix formats and implement the energy minimization. We show results comparing the performance of several cubic-scaling algorithms, and also demonstrate the parallel performance of the linear-scaling solvers, and their supremacy over the cubic-scaling solvers for insulating systems with sizes of several hundreds of atoms.

    Comment: 13 pages, 10 figures
    Keywords Condensed Matter - Materials Science ; Physics - Computational Physics
    Subject code 541
    Publishing date 2022-09-13
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Book ; Online: Colossal phonon drag enhanced thermopower in lightly doped diamond

    Li, Chunhua / Protik, Nakib H / Ordejón, Pablo / Broido, David

    2022  

    Abstract: Diamond is one of the most studied materials because of its unique combination of remarkable electrical, mechanical, thermal and optical properties. Using a fully self-consistent ab initio theory of coupled electron-phonon transport, we reveal another ... ...

    Abstract Diamond is one of the most studied materials because of its unique combination of remarkable electrical, mechanical, thermal and optical properties. Using a fully self-consistent ab initio theory of coupled electron-phonon transport, we reveal another striking behavior: a huge drag enhancement of the thermopower of lightly doped diamond. Thermopower values of around 100,000 microvolts per Kelvin are found at 100 K, significantly exceeding the highest previously measured value in the correlated metal FeSb2, and occurring at much higher temperatures. The enormous thermopower in diamond arises primarily from exceptionally weak anharmonic phonon decay around and below 100 K that facilitates efficient momentum exchange between charge carriers and phonons through electron-phonon interactions. Exceedingly large thermoelectric power factors are also identified. This work gives insights into the physics of the coupled electron-phonon system in solids and advances our understanding of thermoelectric transport in the regime of strong drag.
    Keywords Condensed Matter - Materials Science
    Publishing date 2022-05-24
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Book ; Online: Competition between Ta-Ta and Te-Te bonding leading to the commensurate charge density wave in TaTe4

    Guster, Bogdan / Pruneda, Miguel / Ordejón, Pablo / Canadell, Enric

    2021  

    Abstract: The origin of the charge density wave in TaTe$_4$ is discussed on the basis of a first-principles DFT analysis of the Fermi surface, electron-hole response function, phonon band structure of the average structure and structural optimization of the ... ...

    Abstract The origin of the charge density wave in TaTe$_4$ is discussed on the basis of a first-principles DFT analysis of the Fermi surface, electron-hole response function, phonon band structure of the average structure and structural optimization of the modulated phase. Analysis of the band structure and Fermi surface of the average structure clearly proves that despite the presence of TaTe$_4$ chains in the crystal structure, TaTe$_4$ is in fact a 3D material as far as the electronic structure near the Fermi level is concerned. A Fermi surface nesting mechanism is dismissed as the origin of the 2$a\times2a\times3c$ structural modulation. The optimized 2$a$\xone2$a$\xone3$c$ structure, which is found to be the more stable modulation in agreement with the experimental observations, can be obtained directly from a soft-phonon mode computed for the undistorted structure. Our results suggest that the driving force for the distortion is the maximization of Ta-Ta metal-metal bonding subject to inducing the minimum bonding decrease in the Te sublattice.
    Keywords Condensed Matter - Materials Science
    Subject code 530
    Publishing date 2021-11-21
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Basic aspects of the charge density wave instability of transition metal trichalcogenides NbSe

    Guster, Bogdan / Pruneda, Miguel / Ordejón, Pablo / Canadell, Enric / Pouget, Jean-Paul

    Journal of physics. Condensed matter : an Institute of Physics journal

    2021  Volume 33, Issue 48

    Abstract: ... ...

    Abstract NbSe
    Language English
    Publishing date 2021-09-23
    Publishing country England
    Document type Journal Article
    ZDB-ID 1472968-4
    ISSN 1361-648X ; 0953-8984
    ISSN (online) 1361-648X
    ISSN 0953-8984
    DOI 10.1088/1361-648X/ac238a
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Atomically Sharp Lateral Superlattice Heterojunctions Built-In Nitrogen-Doped Nanoporous Graphene.

    Tenorio, Maria / Moreno, Cesar / Febrer, Pol / Castro-Esteban, Jesús / Ordejón, Pablo / Peña, Diego / Pruneda, Miguel / Mugarza, Aitor

    Advanced materials (Deerfield Beach, Fla.)

    2022  Volume 34, Issue 20, Page(s) e2110099

    Abstract: Nanometer scale lateral heterostructures with atomically sharp band discontinuities can be conceived as the 2D analogues of vertical Van der Waals heterostructures, where pristine properties of each component coexist with interfacial phenomena that ... ...

    Abstract Nanometer scale lateral heterostructures with atomically sharp band discontinuities can be conceived as the 2D analogues of vertical Van der Waals heterostructures, where pristine properties of each component coexist with interfacial phenomena that result in a variety of exotic quantum phenomena. However, despite considerable advances in the fabrication of lateral heterostructures, controlling their covalent interfaces and band discontinuities with atomic precision, scaling down components and producing periodic, lattice-coherent superlattices still represent major challenges. Here, a synthetic strategy to fabricate nanometer scale, coherent lateral superlattice heterojunctions with atomically sharp band discontinuity is reported. By merging interdigitated arrays of different types of graphene nanoribbons by means of a novel on-surface reaction, superlattices of 1D, and chemically heterogeneous nanoporous junctions are obtained. The latter host subnanometer quantum dipoles and tunneling in-gap states, altogether expected to promote interfacial phenomena such as interribbon excitons or selective photocatalysis.
    Language English
    Publishing date 2022-04-10
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1474949-X
    ISSN 1521-4095 ; 0935-9648
    ISSN (online) 1521-4095
    ISSN 0935-9648
    DOI 10.1002/adma.202110099
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  10. Article ; Online: Anion ordering transition and Fermi surface electron-hole instabilities in the (TMTSF)

    Guster, Bogdan / Pruneda, Miguel / Ordejón, Pablo / Canadell, Enric / Pouget, Jean-Paul

    Journal of physics. Condensed matter : an Institute of Physics journal

    2020  Volume 33, Issue 8, Page(s) 85705

    Abstract: The first-principles electron-hole Lindhard response function has been calculated and analyzed in detail for two (TMTSF) ...

    Abstract The first-principles electron-hole Lindhard response function has been calculated and analyzed in detail for two (TMTSF)
    Language English
    Publishing date 2020-10-22
    Publishing country England
    Document type Journal Article
    ZDB-ID 1472968-4
    ISSN 1361-648X ; 0953-8984
    ISSN (online) 1361-648X
    ISSN 0953-8984
    DOI 10.1088/1361-648X/abc406
    Database MEDical Literature Analysis and Retrieval System OnLINE

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