Line data    Source code

       1             : # SPDX-FileCopyrightText: 2024 Pairinteraction Developers
       2             : # SPDX-License-Identifier: LGPL-3.0-or-later
       3             : 
       4             : """Test the Stark map calculation."""
       5             : 
       6           1 : from pathlib import Path
       7             : 
       8           1 : import numpy as np
       9           1 : import pytest
      10             : 
      11           1 : import pairinteraction.real as pi
      12             : 
      13           1 : reference_kets_file = Path(__file__).parent.parent / "data/reference_stark_map/kets.txt"
      14           1 : reference_eigenenergies_file = Path(__file__).parent.parent / "data/reference_stark_map/eigenenergies.txt"
      15           1 : reference_overlaps_file = Path(__file__).parent.parent / "data/reference_stark_map/overlaps.txt"
      16             : 
      17             : 
      18           1 : def test_starkmap(generate_reference: bool) -> None:
      19             :     """Test calculating a Stark map."""
      20             :     # Create a basis
      21           1 :     ket = pi.KetAtom("Rb", n=60, l=0, m=0.5)
      22           1 :     basis = pi.BasisAtom("Rb", n=(58, 62), l=(0, 2))
      23           1 :     print(f"Number of basis states: {basis.number_of_states}")
      24             : 
      25           1 :     electric_fields = np.linspace(0, 10, 11)
      26             :     # Create systems for different values of the electric field
      27           1 :     systems = [pi.SystemAtom(basis).set_electric_field([0, 0, e], unit="V/cm") for e in electric_fields]
      28             : 
      29             :     # Diagonalize the systems in parallel
      30           1 :     pi.diagonalize(systems, diagonalizer="eigen", sort_by_energy=True)
      31             : 
      32             :     # Get the overlap with |ket>
      33           1 :     overlaps = np.array([system.basis.get_overlaps(ket) for system in systems])
      34             : 
      35             :     # Ensure that the overlaps sum up to one
      36           1 :     np.testing.assert_allclose(np.sum(overlaps, axis=1), np.ones(len(electric_fields)))
      37             : 
      38             :     # Compare to reference data
      39           1 :     kets = [repr(ket) for ket in systems[0].basis.kets]
      40           1 :     eigenenergies = np.array([system.get_eigenenergies(unit="GHz") for system in systems])
      41           1 :     eigenvectors = np.array([system.get_eigenbasis().get_coefficients().todense().A1 for system in systems])
      42             : 
      43           1 :     if generate_reference:
      44           1 :         reference_kets_file.parent.mkdir(parents=True, exist_ok=True)
      45           1 :         np.savetxt(reference_kets_file, kets, fmt="%s", delimiter="\t")
      46           1 :         np.savetxt(reference_eigenenergies_file, eigenenergies)
      47           1 :         np.savetxt(reference_overlaps_file, overlaps)
      48           1 :         pytest.skip("Reference data generated, skipping comparison test")
      49             : 
      50           1 :     np.testing.assert_equal(kets, np.loadtxt(reference_kets_file, dtype=str, delimiter="\t"))
      51           1 :     np.testing.assert_allclose(eigenenergies, np.loadtxt(reference_eigenenergies_file))
      52           1 :     np.testing.assert_allclose(overlaps, np.loadtxt(reference_overlaps_file), atol=1e-10)
      53             : 
      54             :     # Because of degeneracies, checking the eigenvectors against reference data is complicated.
      55             :     # Thus, we only check their normalization and orthogonality.
      56           1 :     cumulative_norm = (np.array(eigenvectors) * np.array(eigenvectors).conj()).sum(axis=1)
      57           1 :     np.testing.assert_allclose(cumulative_norm, 90 * np.ones(len(electric_fields)))