cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.24435/materialscloud:az-1p
title: Mott versus hybridization gap in the low-temperature phase of 1T-TaS₂

description: We address the long-standing problem of the ground state of 1T-TaS₂ by computing the correlated electronic structure of stacked bilayers using the GW+EDMFT method. Depending on the surface termination, the semi-infinite uncorrelated system is either band insulating or exhibits a metallic surface state. For realistic values of the on-site and inter-site interactions, a Mott gap opens in the surface state, but it is smaller than the gap originating from the bilayer structure. Our results are consistent with recent scanning tunneling spectroscopy measurements for different terminating layers, and with our own photoemission measurements, which indicate the coexistence of spatial regions with different gaps in the electronic spectrum. By comparison to exact diagonalization data, we clarify the interplay between Mott insulating and band insulating behavior in this archetypal layered system.
DOI: 10.24435/materialscloud:40-28
title: Chemical stability of hydrogen boride nanosheets in water

description: Hydrogen boride sheet is a recently fabricated boron-based two-dimensional nanosheet. For the interest of using it in electronic and catalytic applications, it is important that it has sufficient chemical stability for common substances. In this case, we investigate its chemical stability in water, a common substance in ambient condition and many applications. The study was done using experimental and first-principles method. This record contains the crystal structures, optimized via first-principles calculations that were used in discussing the various properties and interaction between water and hydrogen boride sheet. Additionally, input files used to calculate for the systems were included to aid in reproducing results of the study.
DOI: 10.24435/materialscloud:ft-s8
title: Alloying as a strategy to boost the stability of Copper nanocatalysts during electrochemical CO₂ reduction reaction

description: Cu nano catalysts are among the most promising candidates to enable the up-conversion of CO₂ by means of electrochemical reduction. Yet, the lack of stability of Cu nano catalysts during electrochemical CO₂ reduction reaction represents a strong limiting factor in enabling their widespread use at the industrial level.  The record gathers data related to the theoretical evaluation of the stability and activity of Cu-rich nano catalysts, in the presence of a second metal, namely Ga, whose amount varies between 5% and 30%.
DOI: 10.24435/materialscloud:sy-7b
title: Chemical stability of hydrogen boride nanosheets in water

description: Hydrogen boride sheet is a recently fabricated boron-based two-dimensional nanosheet. For the interest of using it in electronic and catalytic applications, it is important that it has sufficient chemical stability for common substances. In this case, we investigate its chemical stability in water, a common substance in ambient condition and many applications. The study was done using experimental and first-principles method. This record contains the crystal structures, optimized via first-principles calculations that were used in discussing the various properties and interaction between water and hydrogen boride sheet. Additionally, input files used to calculate for the systems were included to aid in reproducing results of the study.
DOI: 10.24435/materialscloud:ja-aj
title: Alloying as a strategy to boost the stability of Copper nanocatalysts during electrochemical CO₂ reduction reaction

description: Cu nano catalysts are among the most promising candidates to enable the up-conversion of CO₂ by means of electrochemical reduction. Yet, the lack of stability of Cu nano catalysts during electrochemical CO₂ reduction reaction represents a strong limiting factor in enabling their widespread use at the industrial level.  The record gathers data related to the theoretical evaluation of the stability and activity of Cu-rich nano catalysts, in the presence of a second metal, namely Ga, whose amount varies between 5% and 30%.
DOI: 10.24435/materialscloud:nn-38
title: In situ high-energy X-ray diffraction of a CuZr-based metallic glass

description: There is much current work on metallic glasses (MGs). The field is making rapid advances and has opened up questions of fundamental scientific interest. Metallic glasses are known to suffer from poor formability. Among other methods of improving the mechanical properties of MGs, introducing deformable crystalline phases into MGs is beneficial for enhancing the plastic compliance of MGs. The definition of the principal phase transformations (on heating and on cooling) underlying the feasibility of such a method is the focus of the deposited in situ high-energy XRD data carried out at Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany. This archive entry contains the temporal evolution of the equilibrium and metastable phases on flash-annealing (heating and cooling) and during containerless solidification via electromagnetic levitation with an unprecedented timescale of ~4 ms.
DOI: 10.24435/materialscloud:r9-xt
title: Torsional stress can regulate the unwrapping of two outer half superhelical turns of nucleosomal DNA

description: Torsional stress has a significant impact on the structure and stability of the nucleosome.  RNA polymerase imposes torsional stress on the DNA in chromatin and unwraps the DNA from the nucleosome to access the genetic information encoded in the DNA.  To understand how the torsional stress affects the stability of the nucleosome, we examined the unwrapping of two half superhelical turns of nucleosomal DNA from either end of the DNA under torsional stress with all-atom molecular dynamics simulations.  The free energies for unwrapping the DNA indicate that positive stress that overtwists DNA facilitates a large-scale asymmetric unwrapping of the DNA without a large extension of the DNA.  During the unwrapping, one end of the DNA was dissociated from H3 and H2A-H2B while the other end of the DNA stably remained wrapped.  The detailed analysis indicates that this asymmetric dissociation is facilitated by the geometry and bendability of the DNA under positive stress.  The geometry stabilized the interaction between the major groove of the twisted DNA and the H3 αN-helix, and the straightened DNA destabilized the interaction with H2A-H2B.  Under negative stress, the DNA became more bendable and flexible, which facilitated the binding of the unwrapped DNA to the octamer in a stable state.  Consequently, we conclude that the torsional stress has a significant impact on the affinity of the DNA and the octamer through the inherent nature of the DNA, and can change the accessibility of regulatory proteins.
DOI: 10.24435/materialscloud:y7-mg
title: In situ high-energy X-ray diffraction of a CuZr-based metallic glass

description: There is much current work on metallic glasses (MGs). The field is making rapid advances and has opened up questions of fundamental scientific interest. Metallic glasses are known to suffer from poor formability. Among other methods of improving the mechanical properties of MGs, introducing deformable crystalline phases into MGs is beneficial for enhancing the plastic compliance of MGs. The definition of the principal phase transformations (on heating and on cooling) underlying the feasibility of such a method is the focus of the deposited in situ high-energy XRD data carried out at Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany. This archive entry contains the temporal evolution of the equilibrium and metastable phases on flash-annealing (heating and cooling) and during containerless solidification via electromagnetic levitation with an unprecedented timescale of ~4 ms.
DOI: 10.24435/materialscloud:dv-bw
title: Torsional stress can regulate the unwrapping of two outer half superhelical turns of nucleosomal DNA

description: Torsional stress has a significant impact on the structure and stability of the nucleosome.  RNA polymerase imposes torsional stress on the DNA in chromatin and unwraps the DNA from the nucleosome to access the genetic information encoded in the DNA.  To understand how the torsional stress affects the stability of the nucleosome, we examined the unwrapping of two half superhelical turns of nucleosomal DNA from either end of the DNA under torsional stress with all-atom molecular dynamics simulations.  The free energies for unwrapping the DNA indicate that positive stress that overtwists DNA facilitates a large-scale asymmetric unwrapping of the DNA without a large extension of the DNA.  During the unwrapping, one end of the DNA was dissociated from H3 and H2A-H2B while the other end of the DNA stably remained wrapped.  The detailed analysis indicates that this asymmetric dissociation is facilitated by the geometry and bendability of the DNA under positive stress.  The geometry stabilized the interaction between the major groove of the twisted DNA and the H3 αN-helix, and the straightened DNA destabilized the interaction with H2A-H2B.  Under negative stress, the DNA became more bendable and flexible, which facilitated the binding of the unwrapped DNA to the octamer in a stable state.  Consequently, we conclude that the torsional stress has a significant impact on the affinity of the DNA and the octamer through the inherent nature of the DNA, and can change the accessibility of regulatory proteins.
DOI: 10.24435/materialscloud:sn-kd
title: Exploring energy landscapes of charge multipoles using constrained density functional theory

description: We present a method to constrain local charge multipoles within density-functional theory. Such multipoles quantify the anisotropy of the local charge distribution around atomic sites and can indicate potential hidden orders. Our method allows selective control of specific multipoles, facilitating a quantitative exploration of the energetic landscape outside of local minima. Thus, it enables a clear distinction between electronically and structurally driven instabilities. We demonstrate the effectiveness of this method by applying it to charge quadrupoles in the prototypical orbitally ordered material KCuF₃. We quantify intersite multipole-multipole interactions as well as the energy-lowering related to the formation of an isolated local quadrupole. We also map out the energy as a function of the size of the local quadrupole moment around its local minimum, enabling quantification of multipole fluctuations around their equilibrium value. Finally, we study charge quadrupoles in the solid solution KCu₁₋ₓZnₓF₃ to characterize the behavior across the tetragonal-to-cubic transition. Our method provides a powerful tool for studying symmetry breaking in materials with coupled electronic and structural instabilities and potentially hidden orders.
DOI: 10.24435/materialscloud:3w-4c
title: Exploring energy landscapes of charge multipoles using constrained density functional theory

description: We present a method to constrain local charge multipoles within density-functional theory. Such multipoles quantify the anisotropy of the local charge distribution around atomic sites and can indicate potential hidden orders. Our method allows selective control of specific multipoles, facilitating a quantitative exploration of the energetic landscape outside of local minima. Thus, it enables a clear distinction between electronically and structurally driven instabilities. We demonstrate the effectiveness of this method by applying it to charge quadrupoles in the prototypical orbitally ordered material KCuF₃. We quantify intersite multipole-multipole interactions as well as the energy-lowering related to the formation of an isolated local quadrupole. We also map out the energy as a function of the size of the local quadrupole moment around its local minimum, enabling quantification of multipole fluctuations around their equilibrium value. Finally, we study charge quadrupoles in the solid solution KCu₁₋ₓZnₓF₃ to characterize the behavior across the tetragonal-to-cubic transition. Our method provides a powerful tool for studying symmetry breaking in materials with coupled electronic and structural instabilities and potentially hidden orders.
DOI: 10.24435/materialscloud:cd-gr
title: Electronic transport across quantum dots in graphene nanoribbons: Toward built-in gap-tunable metal-semiconductor-metal heterojunctions

description: The success of all-graphene electronics is severely hindered by the challenging realization and subsequent integration of semiconducting channels and metallic contacts. Here, we comprehensively investigate the electronic transport across width-modulated heterojunctions consisting of a graphene quantum dot of varying lengths and widths embedded in a pair of armchair-edged metallic nanoribbons, of the kind recently fabricated via on-surface synthesis. We show that the presence of the quantum dot enables the opening of a width-dependent transport gap, thereby yielding built-in one-dimensional metal-semiconductor-metal junctions. Furthermore, we find that, in the vicinity of the band edges, the conductance is subject to a smooth transition from an antiresonant to a resonant transport regime upon increasing the channel length. These results are rationalized in terms of a competition between quantum-confinement effects and quantum dot-to-lead coupling. Overall, our work establishes graphene quantum dot nanoarchitectures as appealing platforms to seamlessly integrate gap-tunable semiconducting channels and metallic contacts into an individual nanoribbon, hence realizing self-contained carbon-based electronic devices.
DOI: 10.24435/materialscloud:3p-zn
title: Electronic transport across quantum dots in graphene nanoribbons: Toward built-in gap-tunable metal-semiconductor-metal heterojunctions

description: The success of all-graphene electronics is severely hindered by the challenging realization and subsequent integration of semiconducting channels and metallic contacts. Here, we comprehensively investigate the electronic transport across width-modulated heterojunctions consisting of a graphene quantum dot of varying lengths and widths embedded in a pair of armchair-edged metallic nanoribbons, of the kind recently fabricated via on-surface synthesis. We show that the presence of the quantum dot enables the opening of a width-dependent transport gap, thereby yielding built-in one-dimensional metal-semiconductor-metal junctions. Furthermore, we find that, in the vicinity of the band edges, the conductance is subject to a smooth transition from an antiresonant to a resonant transport regime upon increasing the channel length. These results are rationalized in terms of a competition between quantum-confinement effects and quantum dot-to-lead coupling. Overall, our work establishes graphene quantum dot nanoarchitectures as appealing platforms to seamlessly integrate gap-tunable semiconducting channels and metallic contacts into an individual nanoribbon, hence realizing self-contained carbon-based electronic devices.
DOI: 10.24435/materialscloud:jy-5c
title: Time-resolved ARPES at LACUS: band structure and ultrafast electron dynamics of solids

description: This record contains the first experimental results obtained at the time-resolved ARPES endstation developed at the Lausanne Centre for Ultrafast Science. The use of VUV photons, generated by means of high-harmonic generation in gas, allows us to explore the out-of-equilibrium electron dynamics over the entire Brillouin zone of solids. In this work we give evidence of this capability by accessing the linearly dispersing surface state of the nodal-line Dirac semimetal ZrSiTe.
DOI: 10.24435/materialscloud:d4-mn
title: First-principles and experimental characterization of the electronic and optical properties of CaS and CaO

description: Doped alkaline-earth chalcogenides are interesting photoluminescent materials for opto-electronic applications. It is crucial to have an extended knowledge about the undoped bulk CaS and CaO since all the excited state properties of the doped material heavily depend on it. In this work we investigate the structural parameters, electronic band structures, macroscopic dielectric constants and absorption spectra for CaS and CaO compounds. Their quasi-particle band structure in the GW approximation yields a value of 4.28 eV and 6.02 eV for the indirect theoretical particle gap of CaS and CaO, respectively. The imaginary part of the macroscopic dielectric function e(omega) is computed including excitonic effects through the Bethe–Salpeter equation. The onset of absorption is within 0.1 eV of the experimental one and the calculated spectrum shows a qualitative agreement with experiment. Our computed exciton binding energies are 0.27 eV and 0.40 eV for CaS and CaO, respectively.
DOI: 10.24435/materialscloud:xh-9w
title: Time-resolved ARPES at LACUS: band structure and ultrafast electron dynamics of solids

description: This record contains the first experimental results obtained at the time-resolved ARPES endstation developed at the Lausanne Centre for Ultrafast Science. The use of VUV photons, generated by means of high-harmonic generation in gas, allows us to explore the out-of-equilibrium electron dynamics over the entire Brillouin zone of solids. In this work we give evidence of this capability by accessing the linearly dispersing surface state of the nodal-line Dirac semimetal ZrSiTe.
DOI: 10.24435/materialscloud:m9-qx
title: First-principles and experimental characterization of the electronic and optical properties of CaS and CaO

description: Doped alkaline-earth chalcogenides are interesting photoluminescent materials for opto-electronic applications. It is crucial to have an extended knowledge about the undoped bulk CaS and CaO since all the excited state properties of the doped material heavily depend on it. In this work we investigate the structural parameters, electronic band structures, macroscopic dielectric constants and absorption spectra for CaS and CaO compounds. Their quasi-particle band structure in the GW approximation yields a value of 4.28 eV and 6.02 eV for the indirect theoretical particle gap of CaS and CaO, respectively. The imaginary part of the macroscopic dielectric function e(omega) is computed including excitonic effects through the Bethe–Salpeter equation. The onset of absorption is within 0.1 eV of the experimental one and the calculated spectrum shows a qualitative agreement with experiment. Our computed exciton binding energies are 0.27 eV and 0.40 eV for CaS and CaO, respectively.
DOI: 10.24435/materialscloud:mx-d3
title: Screening from eg states and antiferromagnetic correlations in d(1,2,3) perovskites: A GW+EDMFT investigation

description: We perform a systematic ab initio study of the electronic structure of Sr(V,Mo,Mn)O3 perovskites, using the parameter-free GW+EDMFT method. This approach self-consistently calculates effective interaction parameters, taking into account screening effects due to nonlocal charge fluctuations. Comparing the results of a 3-band (t2g) description to those of a  5-band (t2g+eg) model, it is shown that the eg states have little effect on the low-energy properties and the plasmonic features for the first two compounds but play a more active role in SrMnO3. In the case of SrMnO3 paramagnetic GW+EDMFT yields a metallic low-temperature solution on the verge of a Mott transition, while antiferromagnetic GW+EDMFT produces an insulating solution with the correct gap size. We discuss the possible implications of this result for the nature of the insulating state above the Neel temperature, and the reliability of the GW+EDMFT scheme.
DOI: 10.24435/materialscloud:wz-fw
title: Screening from eg states and antiferromagnetic correlations in d(1,2,3) perovskites: A GW+EDMFT investigation

description: We perform a systematic ab initio study of the electronic structure of Sr(V,Mo,Mn)O3 perovskites, using the parameter-free GW+EDMFT method. This approach self-consistently calculates effective interaction parameters, taking into account screening effects due to nonlocal charge fluctuations. Comparing the results of a 3-band (t2g) description to those of a  5-band (t2g+eg) model, it is shown that the eg states have little effect on the low-energy properties and the plasmonic features for the first two compounds but play a more active role in SrMnO3. In the case of SrMnO3 paramagnetic GW+EDMFT yields a metallic low-temperature solution on the verge of a Mott transition, while antiferromagnetic GW+EDMFT produces an insulating solution with the correct gap size. We discuss the possible implications of this result for the nature of the insulating state above the Neel temperature, and the reliability of the GW+EDMFT scheme.
DOI: 10.24435/materialscloud:1n-2d
title: Temperature dependence of electronic eigenenergies in the adiabatic harmonic approximation

description: The renormalization of electronic eigenenergies due to electron-phonon interactions (temperature dependence and zero-point motion effect) is important in many materials. We address it in the adiabatic harmonic approximation, based on first principles (e.g., density-functional theory), from different points of view: directly from atomic position fluctuations or, alternatively, from Janak's theorem generalized to the case where the Helmholtz free energy, including the vibrational entropy, is used. We prove their equivalence, based on the usual form of Janak's theorem and on the dynamical equation. We then also place the Allen-Heine-Cardona (AHC) theory of the renormalization in a first-principles context. The AHC theory relies on the rigid-ion approximation, and naturally leads to a self-energy (Fan) contribution and a Debye-Waller contribution. Such a splitting can also be done for the complete harmonic adiabatic expression, in which the rigid-ion approximation is not required. A numerical study within the density-functional perturbation theory framework allows us to compare the AHC theory with frozen-phonon calculations, with or without the rigid-ion approximation. For the two different numerical approaches without non-rigid-ion terms, the agreement is better than 7 μeV in the case of diamond, which represent an agreement to five significant digits. The magnitude of the non-rigid-ion terms in this case is also presented, distinguishing specific phonon modes contributions to different electronic eigenenergies.
DOI: 10.24435/materialscloud:21-ct
title: ONETEP + TOSCAM: uniting dynamical mean field theory and linear-scaling density functional theory

description: We introduce the unification of dynamical mean field theory (DMFT) and linear-scaling density functional theory (DFT), as recently implemented in ONETEP, a linear-scaling DFT package, and TOSCAM, a DMFT toolbox. This code can account for strongly correlated electronic behavior while simultaneously including the effects of the environment, making it ideally suited for studying complex and heterogeneous systems that contain transition metals and lanthanides, such as metalloproteins. We systematically introduce the necessary formalism, which must account for the non-orthogonal basis set used by ONETEP. In order to demonstrate the capabilities of this code, we apply it to carbon monoxide-ligated iron porphyrin and explore the distinctly quantum-mechanical character of the iron 3d electrons during the process of photodissociation.

This archive record contains example input and output files for the DFT, DFT+U, and DFT+DMFT calculations presented in the associated journal article.