## Crystalline.jl

Tools for crystallographic symmetry analysis
Popularity
44 Stars
Updated Last
10 Months Ago
Started In
August 2019

# Crystalline.jl

Tools for crystalline symmetry analysis implemented in the Julia language.

This package provides access e.g. to the symmetry operations of crystalline point groups, space groups, Wyckoff positions, their irreducible representations and band representations, as well as tools for their associated manipulation.

## Installation

The package can be installed via Julia's package manager from the `pkg>` prompt (accessed by typing `]` at the Julia REPL):

`pkg> add Crystalline`

whereafter Crystalline.jl can be loaded via

`julia> using Crystalline`

## Functionality

Crystalline.jl currently provides several functionalities for line groups, plane groups, and space groups, as well as crystallographic point groups.

Example usage includes:

```# construct a 3D `SymOperation` from its triplet form
julia> S"x,-y,-z"
2₁₀₀ ─────────────────────────── (x,-y,-z)
┌ 1  0  0 ╷ 0 ┐
│ 0 -1  0 ┆ 0 │
└ 0  0 -1 ╵ 0 ┘

# load the `SymOperation`s of the 3D space group ⋕16 in a conventional setting
julia> sg = spacegroup(16, Val(3))
SpaceGroup{3} ⋕16 (P222) with 4 operations:
1
2₀₀₁
2₀₁₀
2₁₀₀

# load a dictionary of small irreps and their little groups for space group ⋕16,
# indexed by their k-point labels; then inspect the small irreps at the A point
julia> lgirs = lgirreps(16, Val(3))
julia> lgirs["A"]
LGIrrep{3}: ⋕16 (P222) at A = [α, 0, 1/2]
A₁ ─┬─────────────────────────────────────────────
├─ 1: ──────────────────────────────── (x,y,z)
│     1.0
│
├─ 2₁₀₀: ─────────────────────────── (x,-y,-z)
│     1.0
└─────────────────────────────────────────────
A₂ ─┬─────────────────────────────────────────────
├─ 1: ──────────────────────────────── (x,y,z)
│     1.0
│
├─ 2₁₀₀: ─────────────────────────── (x,-y,-z)
│     -1.0
└─────────────────────────────────────────────

# construct the character table for the small irreps at the Γ point
julia> characters(lgirs["Γ"])
CharacterTable{3}: ⋕16 (P222) at Γ = [0, 0, 0]
──────┬────────────────
│ Γ₁  Γ₂  Γ₃  Γ₄
──────┼────────────────
1 │  1   1   1   1
2₁₀₀ │  1  -1   1  -1
2₀₁₀ │  1  -1  -1   1
2₀₀₁ │  1   1  -1  -1
──────┴────────────────```

Additional functionality includes e.g. point group operations (`pointgroup`) and irreps (`pgirreps`), elementary band representations (`bandreps`), Wyckoff positions (`wyckoffs`), conjugacy classes (`classes`), class-specific characters (`classcharacters`), group generators (`generators`), physically real irreps (`realify`), and Bravais lattice utilities and conventions (accessible via the lightweight stand-alone sub-package Bravais.jl). For a full description of the public API, see the documentation.

### Current limitations

At present, the package's emphasis is on spinless systems (i.e., double groups and spinful irreps are not implemented).

## API stability

Crystalline.jl is a research package in active development: breaking changes are likely (but will respect semantic versioning).

## Citation

If you find this package useful in your reseach, please cite our arXiv paper:

• T. Christensen, H.C. Po, J.D. Joannopoulos, & M. Soljačić, Location and Topology of the Fundamental Gap in Photonic Crystals, Phys. Rev. X 12, 021066 (2022).

In addition, please consider citing any earlier works explicitly referenced in the documentation of individual functions.

### Required Packages

No packages found.