def test_python_imag_time_evolution():
ham, psi0 = _setup_model()
ham_matrix = ham.to_linear_operator()
driver = PyExactTimePropagation(
ham,
dt=TIME,
t0=0.0,
initial_state=psi0,
propagation_type="imaginary",
solver_kwargs={
"atol": ATOL,
"rtol": RTOL
},
)
assert np.allclose(driver.state, psi0)
driver.advance(1)
assert driver.t == TIME
def rhs_imag(t, x):
mean = np.vdot(x, ham_matrix.dot(x))
return -ham_matrix.dot(x) + mean * x
res = solve_ivp(rhs_imag, (0.0, TIME), psi0, atol=ATOL, rtol=RTOL)
psi_scipy = res.y[:, -1]
assert driver.t == approx(res.t[-1])
assert overlap(driver.state, psi_scipy) == approx(1.0)
def test_time_stepping():
ham, psi0 = _setup_model()
driver = PyExactTimePropagation(
ham,
t0=0.0,
dt=0.05,
initial_state=psi0,
propagation_type="real",
solver_kwargs={"atol": 1e-2, "rtol": 1e-2},
)
ts = [driver.t for _ in driver.iter(21)]
ts_ref = np.linspace(0, 1, 21, endpoint=True)
assert np.allclose(ts, ts_ref)