tkwant.manybody.calc_tasks

tkwant.manybody.calc_tasks(intervals, spectra, occupations, keys=None, task_type=<class 'tkwant.onebody.onebody.Task'>, tol=1e-10)[source]

Return all tasks (set of quantum numbers that uniquely identify a onebody state) that will form the manybody state.

Parameters

  • intervals (tkwant.manybody.Interval or sequence thereof) –

    Momentum intervals with quadrature rules for each interval. Each element of intervals must have at least the following attributes:

    • lead : int or tuple of int, lead index

    • band : int, band index (n)

    • kmin : float, lower momentum bound

    • kmax : float, upper momentum bound, must be larger than kmin

    • order : int, quadrature order. See tkwant.integration.calc_abscissas_and_weights

    • quadrature : string, quadrature rule to use. See tkwant.integration.calc_abscissas_and_weights

    • integration_variable : string, variable of integration. Possible values: “energy” : integrate over energy, “momentum”: integrate over momentum

  • spectra (kwantspectrum.spectrum or sequence thereof) – Energy dispersion \(E_n(k)\) of one lead or list thereof in case of several leads.

  • occupations (tkwant.manybody.Occupation or sequence thereof) –

    Each sequence element represents the occupation of a lead. If occupations consistst of only one element or if the sequence has only one element, the occupation is assumed to be identical in each lead. If occupations is a sequence with more than one element, such that the occupation for each lead is different, occupations must have the same length as spectra. Each element of occupations must have at least the following attribute:

    • distribution : callable, thermal distribution function with calling signature (energy)

    If a lead is not occupied, the corresponding element of occupations must be None or False.

  • keys (iterable, optional) – Iterable to generate keys for the tasks dict. Default: Ascending integer sequence (0, 1, 2..), starting at zero.

  • task_type (dataclass, optional) – Data format to store a task in the returned tasks dict. Default: tkwant.onebody.Task

  • tol (float, optional) – Numerical tolerance to remove tasks when their weights are almost zero. Condition to remove a task is |weights| < tol.

Returns

tasks – Dict of all tasks (set of quantum numbers that uniquely identify a onebody state) to set up the manybody wavefunction. Attributes of each tasks element that are modified by this routine:

  • lead : int, lead index

  • mode : int, scattering mode index

  • energy : float, energy of the onebody state

  • momentum : float, momentum of the onebody state; None if unknown

  • weight : float, weighting factor of the one-body state in the manybody sum (weight = math_weight * phys_weight)

  • math_weight : float, mathematical weighting factor

  • phys_weight : float, physical weighting factor

Tasks are ordered as intervals and for each interval by increasing energy.

Return type

dict of task_type

Notes

Momentum values in tasks are only present if integration is performed over momentum (intervals.integration_variable == ‘momentum’).