maxwelllink.tools package

maxwelllink.tools.cosine_drive(amplitude_au=1.0, omega_au=0.1, phase_rad=0.0)[source]

Return a continuous cosine drive.

\[E(t) = A \cos(\omega t + \phi)\]
Parameters:

  • amplitude_au (float, default: 1.0) – Oscillation amplitude in atomic units.

  • omega_au (float, default: 0.1) – Angular frequency in atomic units.

  • phase_rad (float, default: 0.0) – Phase offset in radians.

Returns:

A cosine drive suitable for steady-state excitation.

Return type:

callable

maxwelllink.tools.gaussian_enveloped_cosine(amplitude_au=1.0, t0_au=0.0, sigma_au=10.0, omega_au=0.1, phase_rad=0.0)[source]

Return a Gaussian-enveloped cosine drive.

\[E(t) = A \exp\left(-\frac{(t - t_0)^2}{2 \sigma^2}\right) \cos\bigl(\omega (t - t_0) + \phi\bigr)\]
Parameters:

  • amplitude_au (float, default: 1.0) – Peak field amplitude in atomic units.

  • t0_au (float, default: 0.0) – Temporal center of the pulse in atomic units.

  • sigma_au (float, default: 10.0) – Temporal sigma in atomic units.

  • omega_au (float, default: 0.1) – Angular frequency of the cosine wave in atomic units.

  • phase_rad (float, default: 0.0) – Phase of the cosine wave (radians).

Returns:

A function f(t_au) for use as a time-dependent electric field.

Return type:

callable

maxwelllink.tools.gaussian_pulse(amplitude_au=1.0, t0_au=0.0, sigma_au=10.0)[source]

Return a Gaussian pulse drive.

\[E(t) = A \exp\left(-\frac{(t - t_0)^2}{2 \sigma^2}\right)\]
Parameters:

  • amplitude_au (float, default: 1.0) – Peak field amplitude in atomic units.

  • t0_au (float, default: 0.0) – Temporal center of the pulse in atomic units.

  • sigma_au (float, default: 10.0) – Temporal sigma in atomic units.

Returns:

A function f(t_au) that evaluates the Gaussian pulse at t_au.

Return type:

callable

maxwelllink.tools.ir_spectrum(x, dtfs, N=None, field_description='square', smooth_window_len=11)[source]

Compute an infrared spectrum from a dipole trajectory.

Parameters:

  • x (numpy.ndarray) – Dipole moment trajectory.

  • dtfs (float) – Time step in femtoseconds.

  • N (int or None, optional) – Number of DCT points. None (default) uses x.size. Values greater than x.size result in zero-padding.

  • field_description ({'square', 'none'}, default: 'square') – Field prefactor passed to fft(). Use 'square' for dipole autocorrelation functions and 'none' for velocity autocorrelations.

  • smooth_window_len (int or None, optional) – Window length applied to smooth the spectrum. None disables smoothing. Default is 11.

Returns:

  • numpy.ndarray – Frequencies in \(\text{cm}^{-1}\).

  • numpy.ndarray – Smoothed IR spectral intensities.

Raises:

ValueError – If field_description is not 'square' or 'none'.

maxwelllink.tools.lr_tddft_spectrum(energy_au, e_osc, e_cutoff_ev=30.0, linewidth=1e-2, w_step=1e-5)[source]

Construct an LR-TDDFT spectrum using Lorentzian broadening.

Parameters:

  • energy_au (numpy.ndarray) – Excitation energies in atomic units.

  • e_osc (numpy.ndarray) – Oscillator strengths corresponding to energy_au.

  • e_cutoff_ev (float, default: 30.0) – Upper bound of the returned frequency grid in electron volts.

  • linewidth (float, default: 1e-2) – Lorentzian full width at half maximum in electron volts.

  • w_step (float, default: 1e-5) – Energy grid spacing in electron volts.

Returns:

  • numpy.ndarray – Frequency grid in electron volts.

  • numpy.ndarray – Lorentzian-broadened spectrum.

maxwelllink.tools.rt_tddft_spectrum(mu, dt_au, sp_form='absorption', e_start_ev=0.5, e_cutoff_ev=30.0, sigma=1e5, w_step=1e-5)[source]

Compute an RT-TDDFT spectrum via Pade-approximant Fourier transform.

Parameters:

  • mu (numpy.ndarray) – Time-dependent dipole moment in atomic units.

  • dt_au (float) – Time step in atomic units.

  • sp_form ({'absorption', 'absolute'}, default: 'absorption') – Spectrum representation. 'absorption' returns -omega * Im(mu_tilde(omega)); 'absolute' returns abs(mu_tilde(omega)).

  • e_start_ev (float, default: 0.5) – Lower energy cutoff in electron volts.

  • e_cutoff_ev (float, default: 30.0) – Upper energy cutoff in electron volts.

  • sigma (float, default: 1e5) – Damping factor passed to _pade().

  • w_step (float, default: 1e-5) – Frequency grid spacing in atomic units used by _pade().

Returns:

  • numpy.ndarray – Frequency grid in electron volts.

  • numpy.ndarray – Spectrum on the selected grid with units determined by sp_form.

  • numpy.ndarray – Time grid in femtoseconds.

  • numpy.ndarray – Dipole moment trajectory (identical to the input mu).

Submodules