maxwelllink.tools package

maxwelllink.tools.calc_transverse_components_3d(size=(20, 20, 20), dx=1.0, sigma=1.0, mu12=0.10, local_size=100, component='z')

Calculate the transverse components of a 3D Gaussian polarization distribution.

Parameters:

• size (tuple of float of length 3) – The size of the simulation box in each dimension.

• dx (float) – The spatial resolution (grid spacing) = 1 / resolution.

• sigma (float) – The width of the Gaussian distribution.

• mu12 (float) – The transition dipole moment scaling factor.

• local_size (float) – The size of the local box for FFT calculations, which should be larger than size for convergence.

• component (str) – The component of the polarization to calculate (‘x’, ‘y’, or ‘z’). Default is ‘z’.

maxwelllink.tools.cosine_drive(amplitude_au=1.0, omega_au=0.1, phase_rad=0.0, t_start_au=0.0, t_end_au=1e10)

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.

• t_start_au (float, default: 0.0) – Time before which the drive is zero (atomic units).

• t_end_au (float, default: 1e10) – Time after which the drive is zero (atomic units).

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, t_start_au=0.0, t_end_au=1e10)

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).

• t_start_au (float, default: 0.0) – Time before which the pulse is zero (atomic units).

• t_end_au (float, default: 1e10) – Time after which the pulse is zero (atomic units).

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, t_start_au=0.0, t_end_au=1e10)

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.

• t_start_au (float, default: 0.0) – Time before which the pulse is zero (atomic units).

• t_end_au (float, default: 1e10) – Time after which the pulse is zero (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)

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.k_parallel_pulse(cavity, envelope, omega_au, k_parallel_au, direction='y', center=(0.5, 0.5), size=(0.1, 0.1), amplitude_au=1.0, phase_rad=0.0, target='molecule', projection_axis=None)

Build a multimode pulse with a selected in-plane wave vector.

The returned object is a callable source(t_au) with shape (len(source.excited_grid_list),) for target="molecule" or (len(source.excited_mode_list),) for target="photon". It can be passed directly to maxwelllink.MultiModeSimulation as either molecule_pulse_drive or photon_pulse_drive.

The physical in-plane wave-vector scale is the one used by maxwelllink.FabryPerotCavity’s planar dispersion:

\[\omega_k = \sqrt{\omega_c^2 + k_{\parallel,x}^2 + k_{\parallel,y}^2}.\]

For direction="y", k_parallel_au is mapped to the normalized fractional-coordinate phase by ky_norm = pi * k_parallel_au / cavity.delta_omega_y_au.

Parameters:

• cavity – A FabryPerotCavity instance. It must expose grid_xy and the relevant delta_omega_*_au value.

• envelope (Callable[[float], float] | float) – Time-domain envelope callable envelope(t_au) or constant scalar multiplier. Use helpers such as gaussian_pulse(); the carrier cos(omega_au * t - k*r) is supplied by this function. Passing 1.0 gives a continuous cosine source with grid-dependent phases.

• omega_au (float) – Carrier angular frequency in atomic units.

• k_parallel_au (float) – Physical in-plane wave-vector contribution in atomic units, in the same units as delta_omega_x_au / delta_omega_y_au.

• direction (str) – In-plane propagation direction: "x", "y", "+x", "-x", "+y", or "-y".

• center (Sequence[float]) – Source center (x, y) in fractional cavity coordinates.

• size (Sequence[float]) – Full source window size (size_x, size_y) in fractional cavity coordinates. A smooth Hann window is applied inside this rectangle.

• amplitude_au (float) – Additional peak amplitude multiplier.

• phase_rad (float) – Global carrier phase in radians.

• target (str) – Source target, either "molecule" or "photon". Molecule-targeted sources return one value per selected molecular grid point. Photon- targeted sources project the same spatial source onto cavity modes and return one value per selected mode.

• projection_axis (str | None) – Mode-function component used for photon-target projection. Defaults to "y" for target="photon" and is ignored for target="molecule".

Returns:

Callable source object with attributes including target, excited_grid_list, excited_mode_list, spatial_window, spatial_phase, and k_order.

Return type:

callable

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

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)

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

• maxwelllink.tools.harmonic_oscillator_helper module
  • DummyInitializer
    • DummyInitializer.__init__()
    • DummyInitializer.momentum_initializer()
    • DummyInitializer.position_initializer()
  • DummyThermostat
    • DummyThermostat.__init__()
    • DummyThermostat.apply_kick()
  • LangevinThermostat
    • LangevinThermostat.__init__()
    • LangevinThermostat.apply_kick()
  • MaxwellBoltzmannInitializer
    • MaxwellBoltzmannInitializer.__init__()
    • MaxwellBoltzmannInitializer.momentum_initializer()
    • MaxwellBoltzmannInitializer.position_initializer()
• maxwelllink.tools.ir module
  • auto_correlation_function()
  • fft()
  • ir_spectrum()
  • smooth()
• maxwelllink.tools.pulses module
  • cosine_drive()
  • gaussian_enveloped_cosine()
  • gaussian_pulse()
  • k_parallel_pulse()
• maxwelllink.tools.tddft_spectrum module
  • lr_tddft_spectrum()
  • rt_tddft_spectrum()
• maxwelllink.tools.transverse_components module
  • calc_transverse_components_3d()