# vibrational_analysis

Vibrational analysis.

class daltonproject.vibrational_analysis.VibrationalAnalysis(frequencies: ndarray, ir_intensities: Optional[ndarray] = None, raman_intensities: Optional[ndarray] = None, cartesian_displacements: Optional[ndarray] = None)

Data structure for vibrational properties.

cartesian_displacements: Optional[ndarray]

Alias for field number 3

frequencies: ndarray

Alias for field number 0

ir_intensities: Optional[ndarray]

Alias for field number 1

raman_intensities: Optional[ndarray]

Alias for field number 2

daltonproject.vibrational_analysis.compute_ir_intensities(dipole_gradients: ndarray, transformation_matrix: ndarray, is_linear: bool = False) ndarray

Compute infrared molar decadic absorption coefficient in m^2 / (s * mol).

Parameters
• dipole_gradients – Gradients of the dipole moment (au) with respect to nuclear displacements in Cartesian coordinates.

• transformation_matrix – Transformation matrix to convert from Cartesian to normal coordinates.

• is_linear – Indicate if the molecule is linear.

Returns

IR intensities in m^2 / (s * mol).

daltonproject.vibrational_analysis.compute_raman_intensities(polarizability_gradients: ndarray, polarizability_frequency: float, vibrational_frequencies: ndarray, transformation_matrix: ndarray, is_linear: bool = False) ndarray

Compute Raman differential scattering cross-section in C^4 * s^2 / (J * m^2 * kg).

Parameters
• polarizability_gradients – Gradients of the polarizability with respect to nuclear displacements in Cartesian coordinates.

• polarizability_frequency – Frequency of the incident light in au.

• vibrational_frequencies – Vibrational frequencies in cm^-1.

• transformation_matrix – Transformation matrix to convert from Cartesian to normal coordinates.

• is_linear – Indicate if the molecule is linear.

Returns

Raman intensities in C^4 * s^2 / (J * m^2 * kg).

daltonproject.vibrational_analysis.vibrational_analysis(molecule: Molecule, hessian: ndarray, dipole_gradients: Optional[ndarray] = None, polarizability_gradients: Optional[PolarizabilityGradients] = None)

Perform vibrational analysis.

Parameters
• molecule – Molecule object.

• hessian – Second derivatives with respect to nuclear displacements in Cartesian coordinates.

• dipole_gradients – Gradient of the dipole moment with respect to nuclear displacements in Cartesian coordinates.

• polarizability_gradients – Gradient of the polarizability with respect to nuclear displacements in Cartesian coordinates.

Returns

Harmonic vibrational frequencies (cm^-1). Optionally, IR intensities (m^2 / (s * mol)), Raman intensities (C^4 * s^2 / (J * m^2 * kg)), and transformation matrix.
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