PerovKit

PerovKit provides modular, Pythonic data structures for constructing ligand-passivated ABX₃ perovskite models (nanocrystals, nanorods, and periodic slabs) for downstream atomistic simulations.

Under active development by Seungjun Cha (scha@gatech.edu)

Installation

Requires Python >= 3.12.

git clone https://github.com/sj-cha/PerovKit.git
cd perovkit
pip install -e .

Dependencies: numpy, scipy, ase, rdkit, tqdm

Key Concepts

• Core: The inorganic ABX₃ perovskite structure. Built as either a finite nanocrystal (build_nanocrystal) or a periodic slab (build_slab).
• Ligand: An organic molecule that passivates surface sites. Created from SMILES (from_smiles) or an existing file (from_file). The BindingMotif specifies which atoms coordinate the surface. Cationic ligands take A-sites and anionic ligands take X-sites.
• LigandSpec: Pairs a Ligand with placement parameters: coverage (fraction or absolute count of surface sites), optional binding_sites (explicit site indices), and anchor_offset (controls a vertical offset from the surface).
• NanoCrystal / Slab: Combines a Core with Ligand. Handles site selection and ligand placement by rotation optimization.

Quick Start

from perovkit import Core, Ligand, LigandSpec, BindingMotif, NanoCrystal, Slab

Build a Nanocrystal with Ligands

# 1. Build a 3x3x3 CsPbBr3 core
core = Core.build_nanocrystal(
    A="Cs", B="Pb", X="Br",
    a=5.95,
    supercell=(3,3,3),
    charge_neutral=True,
    random_seed=42,
)

# 2. Define ligands from SMILES or .xyz file
cationic_lig = Ligand.from_smiles(
    smiles="C[NH3+]",
    binding_motif=BindingMotif(["N"]),
    random_seed=42,
    name="MA",
)

anionic_lig = Ligand.from_file(
    filename="ligands/OP.xyz",
    binding_motif=BindingMotif(["O", "O"]),
    name="OP",
)

# 3. Specify coverage and assemble
specs = [
    LigandSpec(ligand=cationic_lig, coverage=0.5),
    LigandSpec(ligand=anionic_lig, coverage=0.5),
]

nc = NanoCrystal(core=core, ligand_specs=specs)
nc.place_ligands()

Build a Slab with Ligands

# Build a 2x2x3 CsPbBr3 slab
core = Core.build_slab(
    A="Cs", B="Pb", X="Br",
    a=5.95,
    supercell=(2,2,3),
)

specs = [
    LigandSpec(ligand=cationic_lig, coverage=0.5),
    LigandSpec(ligand=anionic_lig, coverage=0.5),
]

slab = Slab(core=core, ligand_specs=specs)
slab.place_ligands()

Serialization

Both NanoCrystal and Slab can be exported as a JSON file, alongside the structure file.

# Save
nc.to(fmt="xyz", filename="structure.xyz", write_json=True)

# Load
nc = NanoCrystal.from_file("structure.xyz", "structure.xyz.json")