Crystal and amorphous materials

The escape.scattering.material module provides methods to create instances of material_obj for two types of materials: amorphous and crystal.

escape.scattering.material.unitcell(name, a, b, c, adeg, bdeg, gdeg)

Returns unitcell object for crystal material. Any physical property of unitcell can be a functor representing a gradient change of this property. This functor should be a function of one variable, which will take values in the range of [0; 1].

Returns:

Instance of unitcell_obj

escape.scattering.material.strained_unitcell(name, strain, unitcell_obj refucell)

Returns strained unitcell object for crystal material. Strain can be also a functor representing a gradient change of strain in depth. This functor should be a function of one variable, which will take values in the range of [0; 1].

Parameters:

strain: parameter_obj, double or functor_obj

Strain parameter

‘refucell’: unitcell_obj

Reference unitcell obj, normally substrate.

Returns:

Instance of unitcell_obj

escape.scattering.material.amorphous(name, sld0_re, sld0_im, sldm=None, zvar=None, numslices=None)

Returns amorphous material object. SLDs arguments can have a parameter_obj/value type or can be functors representing a gradient change of the corresponding property with z(depth)-variable or property which depends on wave vector components. In the former case z-variable must be provided togehter with a number of gradient slices.

Parameters:

sld0_re: parameter_obj, double value or functor_obj

Scattering length density, real part

sld0_im: parameter_obj, double value or functor_obj

Scattering length density, imaginary (absorption) part

sldm: parameter_obj, double value or functor_obj

Magnetic scattering length density

zvar: variable_obj

Variable which indicates Z-axis, i.e. normal to the sample surface This variable should be in the domains of all provided functors. Internally it will take values in the range from 0 to 1, indicating upper and lower interfaces of the gradient layer.

numslices: positive integer

Number of slices for all gradient arguments

Returns:

instance of material_obj

escape.scattering.material.crystal(name, sld0_re, sld0_im, sldh_re, sldh_im, sldh_phd, sldm=None, unitcell_obj ucell=None, numslices=None)

Returns crystal material object. Any physical property of material can be a functor representing a gradient change of this property. This functor should be a function of one variable, which will take values in the range of [0; 1].

Parameters:

sld0_re: parameter_obj, double value or functor_obj

Scattering length density, real part

sld0_im: parameter_obj, double value or functor_obj

Scattering length density, imaginary (absorption) part

sldh_re: parameter_obj, double value or functor_obj

An absolute value of a real part of the Bragg diffraction susceptibility multiplied by \(\pi/\lambda^2\)

sldh_im: parameter_obj, double value or functor_obj

An absolute value of an imaginary part of the Bragg diffraction susceptibility multiplied by \(\pi/\lambda^2\)

‘sldh_phd’: double value

Phase difference / \(\pi\) between sldh_re and sldh_im

sldm: parameter_obj, double value or functor_obj

Magnetic scattering length density

‘ucell’: unitcell_obj

Unicell object

‘numslices’: positive integer

Number of slices for all gradient properties

Returns:

instance of material_obj

class escape.scattering.material.unitcell_obj

Container for unitcell parameters.

name

Returns:

Object name.

num_of_params

Returns:

Number of parameters.

parameter(self, size_t i)

class escape.scattering.material.material_obj

Container for material parameters. This class can also represent a material with gradient properties. In this case it consist of slices which you can access using ‘at’ method.

at(self, size_t idx)

Returns:

Material slice if class instance represent a material with gradient properties.

name

num_of_params

numslices

Returns:

Number of slices if material has gradient properties.

parameter(self, size_t i)