qml.qchem.taylor_dipole_coeffs

taylor_dipole_coeffs(pes, max_deg=4, min_deg=1)

Compute fitted coefficients for the Taylor dipole operator.

Parameters

• pes (VibrationalPES) – object containing the vibrational potential energy surface data

• max_deg (int) – maximum degree of Taylor form polynomial

• min_deg (int) – minimum degree of Taylor form polynomial

Returns

a tuple containing:

• list(array(floats)): coefficients for x-displacements

• list(array(floats)): coefficients for y-displacements

• list(array(floats)): coefficients for z-displacements

Return type

tuple

Example

>>> freqs = np.array([0.01885397])
>>> grid, weights = np.polynomial.hermite.hermgauss(9)
>>> pes_onebody = np.array([[0.05235573, 0.03093067, 0.01501878, 0.00420778, 0.0,
...                          0.00584504, 0.02881817, 0.08483433, 0.22025702]])
>>> pes_twobody = None
>>> dipole_onebody = np.array([[[-1.92201700e-16,  1.45397041e-16, -1.40451549e-01],
...                             [-1.51005108e-16,  9.53185441e-17, -1.03377032e-01],
...                             [-1.22793018e-16,  7.22781963e-17, -6.92825934e-02],
...                             [-1.96537436e-16, -5.86686504e-19, -3.52245369e-02],
...                             [ 0.00000000e+00,  0.00000000e+00,  0.00000000e+00],
...                             [ 5.24758835e-17, -1.40650833e-16,  3.69955543e-02],
...                             [-4.52407941e-17,  1.38406311e-16,  7.60888733e-02],
...                             [-4.63820104e-16,  5.42928787e-17,  1.17726042e-01],
...                             [ 1.19224372e-16,  9.12491386e-17,  1.64013197e-01]]])
>>> vib_obj = qml.qchem.VibrationalPES(
...     freqs=freqs,
...     grid=grid,
...     gauss_weights=weights,
...     uloc=None,
...     pes_data=[pes_onebody, pes_twobody],
...     dipole_data=[dipole_onebody],
...     localized=False
... )
>>> x, y, z = qml.qchem.taylor_dipole_coeffs(vib_obj, 4, 2)
>>> print(z)
[array([[ 1.64124324e-03,  5.39120159e-03, -4.80053702e-05]])]

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