"""
Phase ordering evolution visualisation for the 2D XY model.
Quenches from a disordered state to T < T_BKT and records the spin configuration
at multiple time steps, plotting phase configurations, vorticity maps, and
radially averaged correlation functions G(r).
"""
from __future__ import annotations
import argparse
import logging
import numpy as np
from models.xy_model import XYSimulation
from utils.cli_helpers import parse_args_compat
from utils.system_helpers import ensure_results_dir, plot_ordering_evolution, setup_logging
[docs]
def main() -> None:
"""Run the simulation and generate a multi-row phase ordering figure."""
parser = argparse.ArgumentParser(description='2D XY Model Phase Ordering Visualisation')
parser.add_argument('--size', type=int, default=256, help='Linear lattice size L')
parser.add_argument('--temp', type=float, default=0.5, help='Quench temperature T')
parser.add_argument(
'--targets',
type=int,
nargs='+',
default=[1, 10, 100, 1000],
help='MC steps at which to take snapshots',
)
parser.add_argument('--output-dir', type=str, default='results/xy', help='Output directory')
parser.add_argument('--log-file', type=str, default=None, help='Optional log file path')
parser.add_argument('--verbose', action='store_true', help='Enable verbose logging')
args = parse_args_compat(parser)
# Configure logging
log_level = logging.DEBUG if args.verbose else logging.INFO
logger = setup_logging(level=log_level, log_file=args.log_file)
L = args.size
T = args.temp
STEP_TARGETS = sorted(args.targets)
T_BKT: float = 0.893
logger.info(f'XY phase ordering evolution (L={L}, T={T})')
logger.info(f'Recording snapshots at steps {STEP_TARGETS} ...')
sim = XYSimulation(size=L, temp=T, update='random')
n_targets: int = len(STEP_TARGETS)
# Storage for snapshots
snapshots: list[np.ndarray] = []
snapshots_vort: list[np.ndarray] = []
snapshots_gr: list[tuple[np.ndarray, np.ndarray]] = []
current_step: int = 0
for _i, target in enumerate(STEP_TARGETS):
steps_to_run = target - current_step
for _ in range(steps_to_run):
sim.step()
current_step = target
if sim.spins is not None:
snapshots.append(sim.spins.copy())
snapshots_vort.append(sim._calculate_vorticity())
snapshots_gr.append(sim._calculate_correlation_function())
logger.debug(
f'Captured snapshot at step {target} (n_v={sim._get_vortex_density():.4f})'
)
logger.info(f'Collected {n_targets} snapshots. Saving figure ...')
title = f'2D XY Model Ordering Evolution - T = {T} (< T_BKT ≈ {T_BKT}), L = {L}'
plot_ordering_evolution(
targets=STEP_TARGETS,
snapshots=snapshots,
gr_data=snapshots_gr,
vorticity_data=snapshots_vort,
title=title,
filename='ordering_evolution.png',
directory=ensure_results_dir(directory=args.output_dir),
is_vector=True,
)
if __name__ == '__main__':
main()