README

Dataset Title
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Density Functional Theory (DFT) Calculations of CrSe2-xSx and LiCrSe2-xSx Solid Solutions

Dataset Description
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This dataset contains complete text output files generated from spin-polarized density functional theory (DFT) calculations performed using QuantumATK V-2023.12-SP1 (Synopsys). The calculations investigate the structural and energetic properties of layered CrSe2-xSx solid solutions and their corresponding lithiated compounds LiCrSe2-xSx.

This dataset has been published for academic research and educational use. It includes data relating to:

- Geometry optimization
- Total energy calculations
- Li binding energy
- Li intercalation voltage
- Structural evolution during lithiation
- Li-ion diffusion calculations, where applicable

Folder Structure
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The dataset is organised according to chemical composition.

Delithiated structures:

CrSe1.75S0.25/
CrSe1.5S0.5/
CrSe1.25S0.75/
CrSeS/
CrSe0.75S1.25/
CrSe0.5S1.5/
CrSe0.25S1.75/
CrS2/

Lithiated structures:

LiCrSe1.75S0.25/
LiCrSe1.5S0.5/
LiCrSe1.25S0.75/
LiCrSeS/
LiCrSe0.75S1.25/
LiCrSe0.5S1.5/
LiCrSe0.25S1.75/
LiCrS2/

Each folder contains QuantumATK output files (*.txt) corresponding to successfully converged, symmetry-inequivalent atomic configurations for that composition.

Configuration Generation
------------------------
The CrSe2-xSx solid solutions were generated from a 2 x 2 x 2 supercell of the parent CrSe2 structure.

For each composition:

1. All possible Se/S substitutional configurations were generated.
2. Symmetry analysis was performed to identify the symmetry-inequivalent configurations.
3. Each unique configuration was fully optimized using the SCAN exchange-correlation functional.
4. The same procedure was repeated for the corresponding lithiated structures (LiCrSe2-xSx).

DFT Methodology
---------------
All geometry optimizations were performed using:

- QuantumATK V-2023.12-SP1
- Spin-polarized density functional theory
- SCAN meta-GGA exchange-correlation functional
- PseudoDojo pseudopotentials
- High-quality localized basis set
- k-point density: 4 x 4 x 4
- Density mesh cut-off: 140 Hartree
- Electronic convergence criterion: 1 x 10^-4 eV
- Force convergence criterion: 0.02 eV Angstrom^-1

The optimized structures were subsequently used for the calculation of binding energies, intercalation voltages, and Li diffusion barriers.

Contents of Each Output File
----------------------------
Each QuantumATK output file contains the complete record of one DFT geometry optimization, including:

- Initial crystal structure
- Lattice vectors and lattice parameters
- Atomic coordinates
- Calculation settings
- Parallel-computing information
- Self-consistent field (SCF) convergence history
- Geometry-optimization history
- Total energies for the optimization steps
- Atomic forces
- Stress tensor
- Magnetic information, where present
- Final optimized structure
- Final total energy

These text files are the calculation outputs produced directly by QuantumATK.

File Naming Convention
----------------------
Example:

Opt_En_Scan_LiCrSe0.75S1.25-133_98467.txt

The filename components have the following meanings:

Opt_En
    Geometry optimization and total-energy calculation.

Scan
    SCAN meta-GGA exchange-correlation functional.

LiCrSe0.75S1.25
    Chemical composition.

133
    Unique symmetry-inequivalent configuration identifier.

98467
    SLURM job identification number assigned during the calculation.

.txt
    QuantumATK text output file.

Associated files ending with:

_err.txt

contain the standard error output generated during execution. For successful calculations, these files are generally empty.

Missing Calculations
--------------------
Not every theoretically generated configuration is included in this dataset.

Some lithiated or delithiated structures could not be successfully optimized because the geometry optimization did not converge within the specified convergence criteria or the structure evolved into an unstable configuration during relaxation. Such calculations were excluded from subsequent analyses and are therefore absent from the dataset.

Only successfully converged structures for both the delithiated and lithiated phases were used in the energy calculations.

Software Required
-----------------
The raw data are stored as plain text files and can be opened using any standard text editor.

To reproduce or continue the calculations, the following software is required:

- QuantumATK V-2023.12-SP1 (Synopsys)

No proprietary file format is required to read the supplied .txt files.

Abbreviations
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DFT
    Density Functional Theory

SCF
    Self-Consistent Field

SCAN
    Strongly Constrained and Appropriately Normed meta-GGA functional

NEB
    Nudged Elastic Band

Li
    Lithium

Cr
    Chromium

Se
    Selenium

S
    Sulfur

Academic Use
------------
This dataset has been published for academic research and educational use.

Users should acknowledge and cite the deposited dataset record when using or redistributing these data. No specific reuse licence is stated in this README; users should follow the licence and terms displayed on the repository record.