1,720,995 research outputs found
Suppressing The Ferroelectric Switching Barrier in Hybrid Improper Ferroelectrics
No full textThere are two main parts in this work: 1. Strain-tolerance Ruddlesden-Popper perovskite oxides phase diagram. All the density-functional theory based relaxed crystal structures, used in the main text, are included. 2. Polarization switching paths of Ruddlesden-Popper perovskite oxides. We also include Python scripts that are used to analyse the energy, polarization and octahedral rotation angle of a specific crytal structure.Integration of ferroelectric materials in novel technological applications requires low coercive field materials, and consequently, design strategies to reduce the ferroelectric switching barriers. In this first principles study, we show that biaxial strain, which has a strong e ect on the ferroelectric ground
states, can also be used to tune the switching barrier of hybrid improper ferroelectric Ruddlesden-Popper oxides. We identify the region of the strain-tolerance factor phase diagram where this intrinsic barrier is suppressed, and show that it can be explained in relation to strain induced phase transitions to nonpolar phases.This work was supported primarily by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-2011401Birol, Turan; Li, Shutong. (2020). Suppressing The Ferroelectric Switching Barrier in Hybrid Improper Ferroelectrics. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/hvr3-bg02
Data files of work on LaCoO3 using VASP
No full textINCAR file (VASP input file for LaCoO3)
Band structures (agr format)
Wannier functions (xsf format)Sample VASP input file used to study LaCoO3 (INCAR)
Band structures of LaCoO3 at each values of strain (used to determine carrier effective mass)
Wannier functions derived from e_g orbitals of LaCoO3 (used to determine splitting between dx2-y2 and dz2 orbitals)UMN MRSEC under Award No. DMR-1420013Paul, Arpita; Birol, Turan. (2020). Data files of work on LaCoO3 using VASP. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/nq7t-z663
Supporting data for Metallic line defect in wide-bandgap transparent perovskite BaSnO₃
No full textThe atomic and electronic structures of the unique line defect is computationally explored by employing DFT-based simulations.
Simulations use QuantumEspresso, Wien2k, and TEMSIM packages.A line defect with metallic characteristics has been found in optically transparent BaSnO₃ perovskite thin films. The distinct atomic structure of the defect core, composed of Sn and O atoms, was visualized by atomic-resolution scanning transmission electron microscopy (STEM). When doped with La, dopants that replace Ba atoms preferentially segregate to specific crystallographic sites adjacent to the line defect. The electronic structure of the line defect probed in STEM with electron energy-loss spectroscopy was supported by ab initio theory, which indicates the presence of Fermi level–crossing electronic bands that originate from defect core atoms. These metallic line defects also act as electron sinks attracting additional negative charges in these wide-bandgap BaSnO₃ films.Yun, Hwanhui; Topsakal, Mehmet; Prakash, Abhinav; Jalan, Bharat; Jong Seok, Jeong; Birol, Turan; Mkhoyan, K Andre. (2021). Supporting data for Metallic line defect in wide-bandgap transparent perovskite BaSnO₃. Retrieved from the Data Repository for the University of Minnesota (DRUM), https://doi.org/10.13020/c87s-tk09
Strain effect on the ground-state crystal structure of Sr2SnO4 Ruddlesden-Popper oxides
No full textStructure and input files for the first-principles calculations.Simulation data for a manuscript 'Strain effect on the ground-state structure of Sr2SnO4 Ruddlesden-Popper oxides'.
Key data including structures and input files for structural relaxation and phonon calculation of various phases in Sr2SnO4 are included.Yun, Hwanhui; Gautreau, Dominique; Mkhoyan, K. Andre; Birol, Turan. (2022). Strain effect on the ground-state crystal structure of Sr2SnO4 Ruddlesden-Popper oxides. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/x4rh-tv45
Simulation data from: Free carrier induced ferroelectricity in layered perovskites
No full textThe first-principles simulation result of the paper "Free carrier induced ferroelectricity in layered perovskites", including:
1. Input and output for Vienna Ab initio Simulation Package.
2. Code for data analysis using Jupyter notebooks.Doping ferroelectrics with carriers is often detrimental to polarization. This makes the design and discovery of metals that undergo a ferroelectric-like transition challenging. In this letter, we show from first principles that the oxygen octahedral rotations in perovskites are often enhanced by electron doping, and this can be used as a means to strengthen the structural polarization in certain hybrid-improper ferroelectrics -- compounds in which the polarization is not stabilized by the long range Coulomb interactions but is instead induced by a trilinear coupling to octahedral rotations. We use this design strategy to predict a cation ordered Ruddlesden-Popper compound that can be driven into a metallic ferroelectric-like phase via electrolyte gating.Li, Shutong; Birol, Turan. (2021). Simulation data from: Free carrier induced ferroelectricity in layered perovskites. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/wxmc-x946
ProDenCeR
No full textThe code contains many functions useful for manipulating charge/spin densities obtained from DFT. In the present version, the supported DFT codes are only Abinit and VASP. The tools contained in the code allow for plotting isosurfaces of the densities but also doing calculations with them, such as taking numerical integrals, translating the densities, creating real space grids and more. The two main functionalities that the code was developed to have are: (1) projecting the densities onto the irreducible representations of crystallographic space groups; (2) calculating the atomic electric/magnetic multipoles.
The code was developed in the context of understanding altermagnetism, thus in the "examples" directory one can find several examples of using the code to diagnose the ferroic order of magnetic octupoles and 32-poles in collinear altermagnets.
If you have suggestions, encounter issues, or want to check for updates, feel free to visit the project on GitHub: https://github.com/lucabuia/prodencerProDenCeR (Project Densities onto Cubic/tesseral harmonics \& Representations) is a Python library that projects first-principles electron and spin densities onto atomic multipoles and space group representations, enabling quantitative and visual analysis of complex electronic and magnetic states.NSF CAREER grant DMR-2046020Buiarelli, Luca; Jung, Seongjoo; Park, Hyeonseo; Birol, Turan. (2025). ProDenCeR. Retrieved from the Data Repository for the University of Minnesota (DRUM), https://doi.org/10.13020/mwmz-ym10
Raman spectroscopy data and phonon calculations for ScV6Sn6 in P6/mmm and R-3m structures, 2023
No full textThe "phonon_calc" directory contains bash and Python 3 scripts for generating density functional theory input files for use with the Vienna Ab Initio Simulation Package (VASP). The "plotting" directory contains MATLAB scripts for plotting the figures in the related publication. The "TdepRaman_ScVSn" directory contains experimental Raman spectroscopy data used in the related publication.We use density functional theory (DFT) to calculate the phonon frequencies and the distortions associated with them in the compound ScV6Sn6 in the P6/mmm and R-3m space groups, then compute the overlap between the Raman-active phonons in each structure. This data includes scripts to generate the DFT submission files, the results of those simulations, as well as MATLAB scripts to plot the results. We also include experimental Raman spectroscopy data at temperatures from 5.5 K to 300 K.Work at the University of Minnesota (ETR and TB) was supported by NSF CAREER grant DMR-2046020.Ritz, Ethan T; Birol, Turan; Gu, Yanhong; Musfeldt, Janice L. (2023). Raman spectroscopy data and phonon calculations for ScV6Sn6 in P6/mmm and R-3m structures, 2023. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/bchr-e775
Data for Electronic and structural properties of Rh- and Pd-based kagome-layered shandites from first principles
No full textTwo folders are included: Abinit and Structures. The Structures directory contains the relaxed shandite structures of all the 20 materials simulated in the paper, in the format of .cif files. These files are human readable but can also be opened with the VESTA software or other similar software for visualization. The Abinit directory contains all the input files needed for replicating the calculations whose results are presented in the paper. Abinit 9.10.1 was used, which can be downloaded from [1]. All the calculations used PBEsol of the type PAW JTH v1.1, stringent accuracy and xml format obtained from PseudoDojo [2]. For simplicity, all the Abinit files are given only for the case of Rh3Bi2S2, but one can simply change the names of the atoms and change the structural parameters to run calculations for any of the other 19 compounds.
[1] https://www.abinit.org/
[2] https://www.pseudo-dojo.org/First-principles study of shandites M3A2Ch2, with M=Pd,Rh, A=Bi,In,Pb,Sn,Tl and Ch=S,Se. The density functional theory (DFT) and density functional perturbation theory (DFPT) were carried out using Abinit and the dataset contains all the input files needed to reproduce the results. The dataset contains also the cif files containing the relaxed shandite structure of each compound.Work at the University of Minnesota (L.B. and T.B.) were supported by the NSF CAREER grant DMR-2046020.M.H.C. is supported by ERC grant project 101164202 -- SuperSOC. Funded by the European Union.Buiarelli, Luca; Birol, Turan; Andersen, Brian M; Christensen, Morten H. (2025). Data for Electronic and structural properties of Rh- and Pd-based kagome-layered shandites from first principles. Retrieved from the Data Repository for the University of Minnesota (DRUM), https://doi.org/10.13020/eb0t-x263
Chemical bonding and Born charge in 1T-HfS2
No full textTwo main parts of simulations are included in this dataset:
1. Density functional theory: the input and output for Vienna Ab-initio Simulation Package (VASP) used in this publication, which include:
POSCAR: Crystal structure files.
INCAR: Input parameters.
KPOINTS: Input parameters (for k-mesh).
VASPRUN.XML: A formatted output.
2. Wannier function: the input and output for Wannier90, which includes:
wannier90.win: Input parameters.
wannier90.wout: A formatted output.We combine infrared absorption and Raman scattering spectroscopies to explore the properties of 1T-HfS2- a heavy transition metal chalcogenide with strong spin-orbit coupling due to incorporation of the 5d center. We employ the LO-TO splitting of the Eu mode along with a reevaluation of mode mass, unit cell volume, and dielectric constant to reveal the Born effective charge. We find ZB*= 5.33e, in excellent agreement with complementary first principles calculations. In addition to resolving controversy over the nature of chemical bonding in this system, we decompose the Born charge into polarizability and local (ionic) charge. We find α= 5.07 Å3 and Z*= 5.19e, respectively. In order to understand how ZB* relates to the nominal 4+ charge of the Hf center, we decompose the theoretical Born effective charge into band-by-band contributions, and find that polar displacement-induced charge transfer from sulfur p to hafnium d orbitals is responsible for the enhancement of Born charge. 1T-HfS2 is thus an ionic crystal with strong and dynamic covalent effects.The work at the University of Minnesota is supported primarily by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-2011401.Neal, Sabine N; Li, Shutong; Birol, Turan; Musfeldt, Janice L. (2021). Chemical bonding and Born charge in 1T-HfS2. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/jyp2-qd29
Dopant segregation inside and outside dislocation cores in perovskite BaSnO 3 and reconstruction of the local atomic and electronic structures
No full textStructure and input files for the anti-phase boundary in BaSnO3 relaxation simulation.Distinct dopant behaviors inside and outside dislocation cores are identified by atomic-resolution electron microscopy in perovskite BaSnO3 with considerable consequences on local atomic and electronic structures. Driven by elastic strain, when A-site designated La dopants segregate near a dislocation core, the dopant atoms accumulate at the Ba sites in compressively strained regions. This triggers formation of Ba-vacancies adjacent to the core atomic sites resulting in reconstruction of the core. Notwithstanding the presence of extremely large tensile strain fields, when La atoms segregate inside the dislocation core, they become B-site dopants, replacing Sn atoms and compensating the positive charge of the core oxygen vacancies. Electron energy-loss spectroscopy shows that the local electronic structure of these dislocations changes dramatically due to segregation of the dopants inside and around the core ranging from formation of strong La-O hybridized electronic states near the conduction band minimum to insulator-to-metal transition.Yun, Hwanhui; Prakash, Abhinav; Birol, Turan; Jalan, Bharat; Mkhoyan, K. Andre. (2021). Dopant segregation inside and outside dislocation cores in perovskite BaSnO 3 and reconstruction of the local atomic and electronic structures. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/y84x-dg79
- …
