ScatteringFitComponentLobato#

class pyxem.components.ScatteringFitComponentLobato(elements, fracs, N=1.0, C=0.0)[source]#

Bases: Component

A scattering component to fit background atomic scattering. Calculates the sum of the squares sum_squares = sum (ci * fi**2 ) and the square of the sum square_sum = (sum(ci * fi))**2 for atomic fraction ci with electron scattering factor fi. The latter is used for normalisation.

N and C are fitting parameters for the Component class.

The fitted function f is of the form:

f = sum(fi), fi = ai(2 + bi*g^2) / (1 + bi*g^2)^2 where 1 < i < 5, ai, and bi are tabulated constants, and g = 1/d = 2sin(theta)/lambda is the scattering vector magnitude. The factors are tabulated in ATOMIC_SCATTERING_PARAMS_LOBATO.

The parametrisation is detailed in [1].

Parameters:

  • elements (list of str) – A list of elements present (by symbol).

  • fracs (list of float) – A list of fraction of the respective elements. Should sum to 1.

  • N (float) – The “slope” of the fit.

  • C (float) – An additive constant to the fit.

References

[1] Lobato, I., & Van Dyck, D. (2014). An accurate parameterization for scattering factors, electron densities and electrostatic potentials for neutral atoms that obey all physical constraints. Acta Crystallographica Section A: Foundations and Advances, 70(6), 636-649.

Attributes

ScatteringFitComponentLobato.trait_added

An event fired when a new trait is dynamically added to the object.

ScatteringFitComponentLobato.trait_modified

An event that can be fired to indicate that the state of the object has been modified.

Methods

ScatteringFitComponentLobato.function(x)

The actual fitted function.