cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.24435/materialscloud:8z-v4
title: Thermomechanical properties of honeycomb lattices from internal-coordinates potentials

description: Lattice dynamics in low-dimensional materials and, in particular, the quadratic behaviour of the flexural acoustic modes play a fundamental role in their thermomechanical and thermal transport properties. A first-principles evaluation of these can be computationally very demanding, and can be affected by numerical noise which breaks translational and/or rotational invariance. In order to overcome these challenges in honeycomb lattices, we consider the Gartstein internal-coordinate potential where we tune its 13 parameters on first-principles calculations of the interatomic force constants for graphene. We show that the resulting potential not only reproduces very well the phonon dispersions of graphene, but that it can also describe the vibrational properties of carbon nanotubes of any diameter and chirality, without any additional modifications to its analytic expression or parametrization. In addition, one can augment its functional form with a single cubic term that allows also to be able to reproduce the dominant anharmonic terms of the interactions and obtain a close estimate for the lattice thermal conductivity.
Finally, this potential form works well also for other 2D honeycomb materials, such as a monolayer of boron-nitride, provided it is fitted on the short range (analytical) part of the interatomic force constants, and augmented thereafter with the long range dielectric contribution. These considerations underscore how in polar materials potentials based on short-ranged descriptors should be fit to the short-range part of the first-principles interactions, and complemented by long-range analytical dielectric models also parametrized by the same first-principles calculations.
In this entry, we provide a fully open-source implementation of the potential, for graphene, boron nitride, and carbon nanotubes. To guide the reader, we include examples of phonon calculation for all these systems.
DOI: 10.24435/materialscloud:fq-sm
title: Motif based high-throughput structure prediction of superconducting monolayer titanium boride

description: Two-dimensional boron structures, due to the diversity of properties, attract great attention because of their potential applications in nanoelectronic devices. A series of TiB_x (4≤x≤11) monolayers are efficiently constructed through our motif based method and theoretically investigated through high-throughput first-principles calculations. The configurations are generated based on motifs of boron triangular/quadrilateral fragments and multicoordinate titanium-centered boron molecular wheels. Besides priviously reported TiB4 which was discovered by global search method, we predict that high symmetry monolayers TiB7 (Cmmm) and TiB9 (P31m) which are octa-coordinate and nona-coordinate titanium boride are thermodynamic stable. The TiB7 monolayer is a BCS superconductor with the transition temperature Tc up to 8K. The motif based approach is proved to be efficient in searching stable structures with a prior knowledge so that the potentially stable transition metal monolayers can be quickly constructed by using basic cluster motifs. As an efficient way of discovering materials, the method is easily extended to predict other type of materials which have common characteristic pattern in the structure.
DOI: 10.24435/materialscloud:2019.0040/v1
title: Supplementary Data for "Non-Abelian band topology in noninteracting metals"

description: Electron energy bands, which are studied to explain electronic and optical properties of crystalline solids, often exhibit degeneracies called band-structure nodes. Here, we introduce non-Abelian topological charges that characterize line nodes inside the momentum space of -symmetric crystalline metals with weak spin-orbit coupling. We show that these are quaternion charges, similar to those describing disclinations in biaxial nematics. Starting from two-band considerations, we develop the complete many-band description of nodes in the presence of and mirror symmetries, which allows us to investigate the topological stability of nodal chains in metals. The non-Abelian charges put strict constraints on the possible nodal line configurations. Our analysis goes beyond the standard approach to band topology and implies the existence of 1D topological phases not present in existing classifications.
DOI: 10.24435/materialscloud:4k-51
title: Thermomechanical properties of honeycomb lattices from internal-coordinates potentials: the case of graphene and hexagonal boron nitrides

description: Lattice dynamics in low-dimensional materials and, in particular, the quadratic behaviour of the flexural acoustic modes play a fundamental role in their thermomechanical properties. A first-principles evaluation of these can be very demanding, and can be affected by numerical noise that breaks translational or rotational invariance. In order to overcome these challenges, we study the Gartstein internal-coordinate potential and tune its 13 parameters on the first-principles interatomic force constants for graphene. We show that the resulting potential not only reproduces very well the phonon dispersions of graphene, but also those of carbon nanotubes of any diameter and chirality. The addition of a cubic term allows also to reproduce the dominant anharmonic terms, leading to a very good estimate of the lattice thermal conductivity. Finally, this potential form works very well also for boron nitride, provided it is fitted on the short-range (analytical) part of the interatomic force constants, and augmented thereafter with the long-range dielectric contribution. This consideration underscores how potentials based on short-ranged descriptors should be fit, in polar materials, to the short-range part of the first-principles interactions, and complemented by long-range analytical dielectric models parametrized on the same first-principles calculations.
In this entry, we provide a fully open-source implementation of the potential, for graphene, boron nitride, and carbon nanotubes. To guide the reader, we include examples of phonon calculation for all these systems. We also add the second and third derivatives for graphene, both from DFT-PBE and ICP calculations.
DOI: 10.24435/materialscloud:nt-t6
title: Supplementary Data for "Non-Abelian band topology in noninteracting metals"

description: Electron energy bands, which are studied to explain electronic and optical properties of crystalline solids, often exhibit degeneracies called band-structure nodes. Here, we introduce non-Abelian topological charges that characterize line nodes inside the momentum space of -symmetric crystalline metals with weak spin-orbit coupling. We show that these are quaternion charges, similar to those describing disclinations in biaxial nematics. Starting from two-band considerations, we develop the complete many-band description of nodes in the presence of and mirror symmetries, which allows us to investigate the topological stability of nodal chains in metals. The non-Abelian charges put strict constraints on the possible nodal line configurations. Our analysis goes beyond the standard approach to band topology and implies the existence of 1D topological phases not present in existing classifications.
DOI: 10.24435/materialscloud:2019.0045/v1
title: Negatively-curved warped nanographene self-assembled on metal surfaces

description: In this work we characterize  a conjugated polycyclic hydrocarbon containing multiple nonbenzenoid rings and exhibiting negative curvature—the warped nanographene C80H30. The record contains input files to reproduce the calculations discussed in the manuscript and the raw data of the experimental images discussed.
DOI: 10.24435/materialscloud:4c-dn
title: Thermomechanical properties of honeycomb lattices from internal-coordinates potentials: the case of graphene and hexagonal boron nitrides

description: Lattice dynamics in low-dimensional materials and, in particular, the quadratic behaviour of the flexural acoustic modes play a fundamental role in their thermomechanical properties. A first-principles evaluation of these can be very demanding, and can be affected by numerical noise that breaks translational or rotational invariance. In order to overcome these challenges, we study the Gartstein internal-coordinate potential and tune its 13 parameters on the first-principles interatomic force constants for graphene. We show that the resulting potential not only reproduces very well the phonon dispersions of graphene, but also those of carbon nanotubes of any diameter and chirality. The addition of a cubic term allows also to reproduce the dominant anharmonic terms, leading to a very good estimate of the lattice thermal conductivity. Finally, this potential form works very well also for boron nitride, provided it is fitted on the short-range (analytical) part of the interatomic force constants, and augmented thereafter with the long-range dielectric contribution. This consideration underscores how potentials based on short-ranged descriptors should be fit, in polar materials, to the short-range part of the first-principles interactions, and complemented by long-range analytical dielectric models parametrized on the same first-principles calculations.
In this entry, we provide a fully open-source implementation of the potential, for graphene, boron nitride, and carbon nanotubes. To guide the reader, we include examples of phonon calculation for all these systems. We also add the second and third derivatives for graphene, both from DFT-PBE and ICP calculations.
DOI: 10.24435/materialscloud:2020.0025/v1
title: Energy-based Descriptors for Photo-Catalytically Active Metal-Organic Frameworks Discovery

description: Metal-organic frameworks (MOFs) consist of metal nodes that are connected by organic linkers. They are thus highly chemically tunable materials given the broad range of potential linkers and nodes that can be chosen for their synthesis. Their tunability has recently sparked interest for the development of new MOF photo-catalysts for energy-related applications such as hydrogen (H2) evolution and CO2 reduction. The sheer amount of potentially synthesizable MOFs requires to define descriptors that allow to predict their performance with this aim. Herein we propose a systematic computational protocol to determine two energy-based descriptors that are directly related to the performance of a MOF as a photocatalyst. These descriptors assess the UV-vis light absorption capability and the band energy alignment with respect to redox processes and/or co-catalysts energy levels. High-throughput screening based on cost-effective computations of these features is envisioned to aid the discovery of new promising photoactive systems.
DOI: 10.24435/materialscloud:v9-xs
title: Negatively-curved warped nanographene self-assembled on metal surfaces

description: In this work we characterize  a conjugated polycyclic hydrocarbon containing multiple nonbenzenoid rings and exhibiting negative curvature—the warped nanographene C80H30. The record contains input files to reproduce the calculations discussed in the manuscript and the raw data of the experimental images discussed.
DOI: 10.24435/materialscloud:hf-ba
title: Energy-based Descriptors for Photo-Catalytically Active Metal-Organic Frameworks Discovery

description: Metal-organic frameworks (MOFs) consist of metal nodes that are connected by organic linkers. They are thus highly chemically tunable materials given the broad range of potential linkers and nodes that can be chosen for their synthesis. Their tunability has recently sparked interest for the development of new MOF photo-catalysts for energy-related applications such as hydrogen (H2) evolution and CO2 reduction. The sheer amount of potentially synthesizable MOFs requires to define descriptors that allow to predict their performance with this aim. Herein we propose a systematic computational protocol to determine two energy-based descriptors that are directly related to the performance of a MOF as a photocatalyst. These descriptors assess the UV-vis light absorption capability and the band energy alignment with respect to redox processes and/or co-catalysts energy levels. High-throughput screening based on cost-effective computations of these features is envisioned to aid the discovery of new promising photoactive systems.
DOI: 10.24435/materialscloud:2019.0054/v1
title: Self-consistent site-dependent DFT+U study of stoichiometric and defective SrMnO3

description: We propose a self-consistent site-dependent Hubbard U approach for density functional theory (DFT)+U calculations of defects in complex transition metal oxides, using Hubbard parameters computed via linear response theory. The formation of a defect locally perturbs the chemical environment of Hubbard sites in its vicinity, resulting in different Hubbard U parameters for different sites. Using oxygen vacancies in SrMnO3 as a model system, we investigate the dependence of U on the chemical environment and study its influence on the structural, electronic, and magnetic properties of defective bulk and strained thin-film structures. Our results show that a self-consistent U improves the description of stoichiometric bulk SrMnO3 with respect to generalized gradient approximation (GGA) or GGA+U calculations using an empirical U. For defective systems, U changes as a function of the distance of the Hubbard site from the defect, its oxidation state, and the magnetic phase of the bulk structure. Taking into account this dependence, in turn, affects the computed defect formation energies and the predicted strain- and/or defect-induced magnetic phase transitions, especially when occupied localized states appear in the band gap of the material upon defect creation.
DOI: 10.24435/materialscloud:nx-r2
title: Self-consistent site-dependent DFT+U study of stoichiometric and defective SrMnO3

description: We propose a self-consistent site-dependent Hubbard U approach for density functional theory (DFT)+U calculations of defects in complex transition metal oxides, using Hubbard parameters computed via linear response theory. The formation of a defect locally perturbs the chemical environment of Hubbard sites in its vicinity, resulting in different Hubbard U parameters for different sites. Using oxygen vacancies in SrMnO3 as a model system, we investigate the dependence of U on the chemical environment and study its influence on the structural, electronic, and magnetic properties of defective bulk and strained thin-film structures. Our results show that a self-consistent U improves the description of stoichiometric bulk SrMnO3 with respect to generalized gradient approximation (GGA) or GGA+U calculations using an empirical U. For defective systems, U changes as a function of the distance of the Hubbard site from the defect, its oxidation state, and the magnetic phase of the bulk structure. Taking into account this dependence, in turn, affects the computed defect formation energies and the predicted strain- and/or defect-induced magnetic phase transitions, especially when occupied localized states appear in the band gap of the material upon defect creation.
DOI: 10.24435/materialscloud:wy-kn
title: Revised MD17 dataset

description: The original MD17 dataset (http://quantum-machine.org/datasets/#md-datasets) [Chemiela et al. Sci. Adv. 3(5), e1603015, 2017] contains numerical noise. Thus, any numbers presented from benchmarks on this data are likely flawed. Here, we present a new dataset with negligible numerical noise for benchmarking of forces and energy predictions for molecular dynamics simulations. As the structures are taken from a molecular dynamics simulation (i.e. time series data), they are not guaranteed to be independent samples. This is easily evident from the autocorrelation function for the original MD17 dataset. In short: DO NOT train a model on more than 1000 samples from the revised dataset, and do not train models for more than 50 samples from the original MD17 dataset. Data already published with 50K samples on the original MD17 dataset should be considered meaningless due to this fact and due to the noise in the original data.
DOI: 10.24435/materialscloud:36-57
title: Revised MD17 dataset

description: The original MD17 dataset (http://quantum-machine.org/datasets/#md-datasets) [Chemiela et al. Sci. Adv. 3(5), e1603015, 2017] contains numerical noise. Thus, any numbers presented from benchmarks on this data are likely flawed. Here, we present a new dataset with negligible numerical noise for benchmarking of forces and energy predictions for molecular dynamics simulations. As the structures are taken from a molecular dynamics simulation (i.e. time series data), they are not guaranteed to be independent samples. This is easily evident from the autocorrelation function for the original MD17 dataset. In short: DO NOT train a model on more than 1000 samples from the revised dataset, and do not train models for more than 50 samples from the original MD17 dataset. Data already published with 50K samples on the original MD17 dataset should be considered meaningless due to this fact and due to the noise in the original data.
DOI: 10.24435/materialscloud:2019.0056/v1
title: Overcoming steric hindrance in aryl-aryl homocoupling via on-surface copolymerization

description: On‐surface synthesis is a unique tool for growing low‐dimensional carbon nanomaterials with precise structural control down to the atomic level.
One of the most applied reactions to covalently interlink molecular precursors is dehalogenative aryl‐aryl coupling. 
Failures in this process are often related to the steric hindrance between reactants, which may arise due to their coplanarity upon adsorption on a surface. In a recent work we proposed a copolymerization approach to overcome the limitations that prevent intermolecular homocoupling. We used suitable linkers as additional reactants to demonstrate formation of fully conjugated polycyclic nanowires incorporating non‐benzenoid rings. This record contains data to support the experimental and theoretical evidences discussed in the manuscript.
DOI: 10.24435/materialscloud:17-a0
title: Overcoming steric hindrance in aryl-aryl homocoupling via on-surface copolymerization

description: On‐surface synthesis is a unique tool for growing low‐dimensional carbon nanomaterials with precise structural control down to the atomic level.
One of the most applied reactions to covalently interlink molecular precursors is dehalogenative aryl‐aryl coupling. 
Failures in this process are often related to the steric hindrance between reactants, which may arise due to their coplanarity upon adsorption on a surface. In a recent work we proposed a copolymerization approach to overcome the limitations that prevent intermolecular homocoupling. We used suitable linkers as additional reactants to demonstrate formation of fully conjugated polycyclic nanowires incorporating non‐benzenoid rings. This record contains data to support the experimental and theoretical evidences discussed in the manuscript.
DOI: 10.24435/materialscloud:2019.0055/v1
title: Termini effects on the optical properties of graphene nanoribbons

description: First principles the optical response of finite-length armchair-edged graphene nanoribbons (AGNRs) within the framework of many-body perturbation theory. As a result of the explicit inclusion of zigzag extremities, we identify low-energy and low-intensity excitations that are expected to be almost independent of the GNR length. These excitations coexist with bulk-like excitations, which have the same origin as the ones characterizing infinite AGNRs. Our results are used to rationalize termini effects on the optical response of GNRs and to shed light on recent photoluminescence data.
DOI: 10.24435/materialscloud:nt-vr
title: Termini effects on the optical properties of graphene nanoribbons

description: First principles the optical response of finite-length armchair-edged graphene nanoribbons (AGNRs) within the framework of many-body perturbation theory. As a result of the explicit inclusion of zigzag extremities, we identify low-energy and low-intensity excitations that are expected to be almost independent of the GNR length. These excitations coexist with bulk-like excitations, which have the same origin as the ones characterizing infinite AGNRs. Our results are used to rationalize termini effects on the optical response of GNRs and to shed light on recent photoluminescence data.
DOI: 10.24435/materialscloud:2020.0007/v1
title: Metal-organic frameworks as kinetic modulators for branched selectivity in hydroformylation

description: Finding heterogeneous catalysts that are superior to homogeneous ones for selective organic transformation is a major challenge in catalysis. Here we show how micropores in metal-organic frameworks (MOFs) push homogeneous catalytic reactions into kinetic regimes inaccessible under standard conditions. Such property allows branched selectivity up to 90% in the Co-catalysed hydroformylation of olefins without directing groups, not achievable with existing catalysts. This finding has a big potential in the production of aldehydes for the fine chemical industry. Monte Carlo and density functional theory simulations combined with kinetic models show that the micropores of MOFs with UMCM-1 and MOF-74 topologies increase the olefins density beyond neat conditions while partially preventing the adsorption of syngas leading to high branched selectivity. The easy experimental protocol and the chemical and structural flexibility of MOFs will attract the interest of the fine chemical industries towards the design of heterogeneous processes with exceptional selectivity.
DOI: 10.24435/materialscloud:h8-cf
title: Metal-organic frameworks as kinetic modulators for branched selectivity in hydroformylation

description: Finding heterogeneous catalysts that are superior to homogeneous ones for selective organic transformation is a major challenge in catalysis. Here we show how micropores in metal-organic frameworks (MOFs) push homogeneous catalytic reactions into kinetic regimes inaccessible under standard conditions. Such property allows branched selectivity up to 90% in the Co-catalysed hydroformylation of olefins without directing groups, not achievable with existing catalysts. This finding has a big potential in the production of aldehydes for the fine chemical industry. Monte Carlo and density functional theory simulations combined with kinetic models show that the micropores of MOFs with UMCM-1 and MOF-74 topologies increase the olefins density beyond neat conditions while partially preventing the adsorption of syngas leading to high branched selectivity. The easy experimental protocol and the chemical and structural flexibility of MOFs will attract the interest of the fine chemical industries towards the design of heterogeneous processes with exceptional selectivity.