# DFT dataset: $X$=(Li,Na,Ca,Mg,Al) Intercalation into (F/OH)-Substituted Anatase TiO<sub>2</sub>

This dataset contains inputs and outputs for a series of VASP calculations
considering intercalation of Li, Na, Mg, Ca, and Al into F/OH-substituted anatase 
TiO<sub>2</sub>.

Each VASP calculation directory contains the following files:
- `INCAR`: VASP master input file.
- `KPOINTS`: VASP k-point input file.
- `POSCAR`: VASP structure input file.
- `POTCAR.spec`: This specifies the pseudopotentials used.
- `OUTCAR`: VASP master output file.
- `vasprun.xml`: XML VASP output summary.
- `vaspmeta.yaml`: Additional metadata describing the calculation.

## `POTCAR.spec`

Each calculation directory contains a `POTCAR.spec` file, that specifies the pseudopotentials used
for that calculation.

e.g.
```
Ti_pv PBE_54
```
indicates the `Ti_pv` pseudopotential, from the PBE v.54 has been used.  
The `POTCAR.spec` data has been automatically generated using the `potcar_spec` tool in [`vasppy`][vasppy].

## `vaspmeta.yaml`

Each calculation directory contains a `vaspmeta.yaml` file, that describes additional metadata for that calculation. 

e.g.

```
title: stoichiometric anatase
description: >
    stoichiometric anatase TiO2 3x3x1 supercell.
notes: The lattice parameters were generated by fitting volume-constrained geometry optimised structures for a single unit cell, then imposing the correct spacegroup symmetry of the minimum energy-volume structure.
status: finished  
```

The `title` entry is used in subsequent processing as a unique identifier for each calculation.

## Calculation sets

This data set consists contains four subsets of calculations, each in a separate top-level directory:
```
.
├── README.md
├── elemental_reference
├── stoichiometric
├── anion_location_test
└── vacancy_intercalation
```

### `elemental_reference`

This directory contains elemental reference calculations for Li, Na, Mg, Ca, and Al. More information is given in the [`README.md`](elemental_reference/README.md).

### `stoichiometric`

This directory contains a geometry optimastion of a single anatase Ti4O8 unit cell, performed by fitting to the Murnaghan equation of state, a series of 3x3x1 supercell calculations (stoichiometric, and with Ca, Mg, Li, Al, and Na inserted at an interstitial site), and a stoichiometric 4x4x2 supercell calculation. More information is given in the [`README.md`](stoichiometric/README.md).

### `anion_location_test`

This directory contains a series of calculations performed in 4x4x2 anatase supercells, to assess the relative energies of different configurations of (F,OH)-substituted oxide ions in relation to a charge compensating titanium vacancy. More information is given in the [`README.md`](anion_location_test/README.md).

### `vacancy_intercalation`

This directory contains a series of calculations for Li, Na, Mg, Ca, and Al inserted into the titanium vacancy in 3x3x1 anatase supercells. Each subdirectory contains calculations with a different set of 4(F,OH) anions substituting the 4 oxide ions in equatorial positions of the Ti vacancy octahedron. More information is given in the [`README.md`](vacancy_intercalation/README/md).
 
[vasppy]: `vasppy`: A Python suite for manipulating VASP input and output, https://github.com/bjmorgan/vasppy.