Data associated with "Displacive Jahn--Teller transition in NaNiO2"

This data repository contains the data associated with the paper "Displacive Jahn--Teller transitions in NaNiO₂", published in the ACS Journal of the American Chemical Society in 2024. Authors: Nagle-Cocco, L. A. V.; Genreith-Schriever, A. R.; Steele, J. M. A.; Tacconis, C.; Bocarsly, J. D.; Mathon, O.; Neuefeind, J. C.; Liu, J.; O’Keefe, C. A.; Goodwin, A. L.; Grey, C. P.; Evans, J. S. O.; Dutton, S. E. For any queries, contact Liam Nagle-Cocco ([e-mail]/[e-mail]) or Sian E. Dutton ([e-mail]). ### Contents This data repository contains a file called SI.pdf, which is the supporting information associated with the manuscript. It also contains several folders with additional data. This section lists the folders and their contents within this data repository. * Variable_temperature_synchrotron_diffraction. This folder contains the raw diffraction patterns used in this analysis. It also contains the Topas input file, along with files listing the angles of Bragg reflections, CIF files, and files containing the experimental data, calculated data, and difference patterns. * Raw_neutron_diffraction. This folder contains the neutron diffraction data in real and reciprocal space as used in this study. It also contains the standard Si data measured on 24th March 2021. * Small_box_PDF_analysis. This folder contains the Topas input files used for the small box PDF analysis which is presented in the SI. * Big_box_PDF_analysis. This folder contains the big box PDF analysis input files used for big box PDF analysis both with and without BVS restraints, associated CIF files, and files containing the real- and reciprocal-space fit plots (experimental, calculated, and difference data). This folder does NOT contain the big box PDF analysis at 500 K from a disordered Jahn--Teller-distorted starting structure. The folder contains two subfolders: * d+p: input and output files refined against data and penalties. * p: input and output files refined against penalties only. * Big_box_PDF_analysis_disordered_JT. This folder contains the big box PDF analysis input files used for big box PDF analysis both with and without BVS restraints, associated CIF files, and files containing the real- and reciprocal-space fit plots (experimental, calculated, and difference data). This folder contains only the data at 500 K from a JT-distorted randomly-generated starting structure. This folder also contains the code used to generate these input files. * XAS-data. This folder contains the XAS data and the Python code used to analyse it. Two samples of NaNiO2 were measured on heating and subsequent cooling. These are (1) Ramp_up followed by Ramp_Down, then (2) Ramp_up_2 followed by Ramp_Down_2. The second sample was used in the manuscript because the data was higher quality. Additional data can be found in doi:10.15151/ESRF-ES-962076745. * AIMD. This folder contains the POSCAR files at all studied timesteps from the ab initio molecular dynamics (AIMD) data, at all studied temperatures. AIMD was performed using VASP. The naming of the POSCAR is "POSCAR_ts.[time]" where [time] is the time in femtoseconds. Initial equilibriation timesteps are not included. POSCARs were obtained using OVITO. There are two sets of data: from a JT-distorted colinear start, and a JT-undistorted rhombohedral start. The folder also contains tabulated data for all octahedra at all timesteps. Note that in some of these tabulated data, the calculation of van Vleck parameters by VanVleckCalculator was unsuccessful, and in this case the data is written as "None". * Nuclear_magnetic_resonance. This folder contains the NMR data presented in the SI, in the format which can be opened using Topspin. These are split between two folders: static and magic angle spinning (MAS). Note that the MAS data is not calibrated by temperature and so the claimed temperatures are not accurate.