# DVR-jl

Solves the quantum $n$-body problem in finite volume (lattice) with periodic boundary conditions. Uses discrete variable representation (DVR) with optional support for complex scaling to study resonances. All details can be found in [H. Yu, N. Yapa, and S. König, Complex scaling in finite volume, Phys. Rev. C 109, 014316 (2024)](https://doi.org/10.1103/PhysRevC.109.014316).

## Installation

Make sure you have Julia installed. To install the required packages, follow these steps:

1. Open a terminal in the project root directory.
2. Start Julia with the project environment activated:
   ```bash
   julia --project=.
   ```
3. Enter the package manager mode by pressing `]`.
4. Run the `instantiate` command:
   ```julia
   (DVR-jl) pkg> instantiate
   ```

Alternatively, you can run this single command from your terminal:
```bash
julia --project=. -e 'import Pkg; Pkg.instantiate()'
```

## Usage

See `calculations/3b_bound.jl` for an example on a 3-body bound state.
See `calculations/3b_res_from_paper.jl` for an example of a 3-body resonance via complex scaling.

## Planned features

- [ ] Spin and isospin degrees of freedom for nuclear calculations
- [ ] Multi-node HPC support
- [ ] Parity and cubic symmetries ($S_4$)

## Acknowledgments

The author gratefully acknowledges the guidance from Sebastian König.