Effect of Screened Exact Exchange on First Principles Modelling of Vacancy Defects in Alkali-metal-based Bismuth Oxide (ABiO2; A= Na, K) for Photovoltaic and Photocatalytic Applications

================================================================================ ABiO2 (A = Na, K) Bulk and Defective Structures: DFT-Relaxed Geometries ================================================================================ This dataset contains first-principles density functional theory (DFT) relaxed atomic structures for the alkali-metal bismuth oxides NaBiO2 and KBiO2, together with their intrinsic point-vacancy defects in a range of charge states. The files support the study of native defect thermodynamics in ABiO2 compounds. The two compounds are provided as separate archives (or top-level folders): NaBiO2_Bulk_and_Defective_Structures/ KBiO2_Bulk_and_Defective_Structures/ Both share the same organisation, naming convention, and file format, described below. Compound-specific details (lattice parameters, PAW potentials) are noted where they differ. -------------------------------------------------------------------------------- 1. CONTENTS -------------------------------------------------------------------------------- Within each compound folder there is one sub-folder per structure, each containing a single VASP POSCAR file with the relaxed lattice vectors and fractional atomic coordinates. Bulk/ Pristine ABiO2 supercell (A48 Bi48 O96) V_Bi_0/ Bismuth vacancy, charge state 0 V_Bi_-1/ Bismuth vacancy, charge state -1 V_Bi_-2/ Bismuth vacancy, charge state -2 V_Bi_-3/ Bismuth vacancy, charge state -3 V_A_0/ Alkali-metal (Na or K) vacancy, charge state 0 V_A_-1/ Alkali-metal (Na or K) vacancy, charge state -1 (folders are named V_Na_* or V_K_* in the respective archive) V_O_0/ Oxygen vacancy, charge state 0 V_O_+1/ Oxygen vacancy, charge state +1 V_O_+2/ Oxygen vacancy, charge state +2 Each compound thus provides 1 bulk + 9 defect configurations (10 structures). -------------------------------------------------------------------------------- 2. NAMING CONVENTION -------------------------------------------------------------------------------- Folders are named V_<species>_<q> where: V denotes a vacancy (a missing atom of the given species) <species> is the removed atom: Bi, the alkali metal (Na or K), or O <q> is the defect charge state, using the sign convention that a positive q corresponds to electrons removed from the system (e.g. V_O_+2 is a doubly positively charged oxygen vacancy). Each bulk supercell contains 48 formula units (A48 Bi48 O96, 192 atoms). Each defect cell is built from this supercell with a single atom removed, so: - V_Bi cells contain A48 Bi47 O96 (191 atoms) - V_A cells contain A47 Bi48 O96 (191 atoms) - V_O cells contain A48 Bi48 O95 (191 atoms) -------------------------------------------------------------------------------- 3. FILE FORMAT -------------------------------------------------------------------------------- All structure files are in VASP POSCAR format: Line 1 Comment / label Line 2 Universal scaling factor Lines 3-5 Lattice vectors (Angstrom) Line 6 Element symbols (Na Bi O or K Bi O) Line 7 Number of atoms of each element Line 8 Coordinate mode (Direct / fractional) Line 9+ Atomic positions Approximate orthorhombic supercell dimensions (Angstrom): NaBiO2: 14.65 x 14.79 x 14.29 KBiO2: 16.42 x 15.86 x 14.95 Defect cells share the bulk cell dimensions of their compound (defects were relaxed at fixed cell shape and volume).