pymatgen.analysis.diffraction.neutron module

This module implements a neutron diffraction (ND) pattern calculator.

class NDCalculator(wavelength=1.54184, symprec: float = 0, debye_waller_factors=None)[source]

Bases: AbstractDiffractionPatternCalculator

Computes the powder neutron diffraction pattern of a crystal structure. This code is a slight modification of XRDCalculator in pymatgen.analysis.diffraction.xrd. See it for details of the algorithm. Main changes by using neutron instead of X-ray are as follows:

  1. Atomic scattering length is a constant.

  2. Polarization correction term of Lorentz factor is unnecessary.

Reference: Marc De Graef and Michael E. McHenry, Structure of Materials 2nd ed, Chapter13, Cambridge University Press 2003.

Initializes the ND calculator with a given radiation.

Parameters:

  • wavelength (float) – The wavelength of neutron in angstroms. Defaults to 1.54, corresponds to Cu K_alpha x-ray radiation.

  • symprec (float) – Symmetry precision for structure refinement. If set to 0, no refinement is done. Otherwise, refinement is performed using spglib with provided precision.

  • symbol (debye_waller_factors ({element) – float}): Allows the specification of Debye-Waller factors. Note that these factors are temperature dependent.

get_pattern(structure: Structure, scaled=True, two_theta_range=(0, 90))[source]

Calculates the powder neutron diffraction pattern for a structure.

Parameters:

  • structure (Structure) – Input structure

  • scaled (bool) – Whether to return scaled intensities. The maximum peak is set to a value of 100. Defaults to True. Use False if you need the absolute values to combine ND plots.

  • two_theta_range ([float of length 2]) – Tuple for range of two_thetas to calculate in degrees. Defaults to (0, 90). Set to None if you want all diffracted beams within the limiting sphere of radius 2 / wavelength.

Returns:

(NDPattern)