Getting Started

Installation

pip install rapidity

Or for development:

git clone https://github.com/mkpanfil/rapidity.git
cd rapidity
pip install -e .

Quick Example

Solve the TBA for the Lieb-Liniger model at finite temperature and compute the particle density:

import numpy as np
import matplotlib.pyplot as plt
from rapidity.core import Grid1D
from rapidity.models import LiebLiniger
from rapidity.tba import TBAState
from rapidity.utils import plot

# define model and grid
model = LiebLiniger(c=1.0)
grid = Grid1D.uniform(-5, 5, 200, "theta")

# solve TBA at temperature T=0.5 and chemical potential mu=0.5
T, mu = 0.5, 0.5
state = TBAState.from_betas(model, grid, betas={2: 1/T, 0: -mu/T})

# compute particle density
rho_p = state.rho_p()
N_L = rho_p.integrate().values
print(f"Total density N/L = {N_L:.6f}")

# plot particle density
plot(rho_p)
plt.xlabel(r"$\theta$")
plt.ylabel(r"$\rho_p(\theta)$")
plt.title(f"Lieb-Liniger model at T={T}, mu={mu}")
plt.show()