Parameters¶

class parameters.Parameters(path=None)¶

Collection of parameters.

New instances may optionally be passed a path to a YAML file. See load_file().

parameters = Parameters()
parameters.add_parameter('warp speed', 9.0)
parameters.get_value('warp speed') #=> 9.0

parameters.set_value('warp speed', 10.0)
parameters.get_value('warp speed') #=> 10.0

add_parameter(name, value, meta=None)¶

Add a parameter to the parameter list.

Parameters:	name (str) – New parameter’s name. value (float) – New parameter’s value. meta (dict) – New parameter’s meta property.

get(name)¶

Get a parameter object by name.

Parameters:	name (str) – Name of the parameter object.
Returns:	The parameter.
Return type:	Parameter

get_meta(name)¶

Get the metadata of a parameter by name.

Returns:	Parameter metadata.
Return type:	dict

get_value(name)¶

Get the value of a parameter by name.

Returns:	Parameter value.
Return type:	Parameter

load_file(path)¶

Load a YAML file with parameter data and other metadata.

Parameters:	path (str) – Path to YAML file.

The data in the YAML file is used to set the properties for the instance. The YAML file must contain a parameters key. It may optionally include any keys defined in property_keys.

# data.yml
---
name: Shield frequencies
parameters:
  - name: a
    value: 24.50
  - name: β
    value: 42.10
    meta:
      phase_inverted: true

parameters = Parameters('data.yml')
parameters.name #=> 'Shield frequencies'
parameters.get_value('a') #=> 24.50
parameters.get_meta('β')['phase_inverted'] #=> true

name¶

The name of this parameter set.

Returns:	Parameter set name.
Return type:	str
Default:	None

static parameter_list(data)¶

Create a list of parameter objects from a dict.

Parameters:	data (dict) – Dictionary to convert to parameter list.
Returns:	Parameter list.
Return type:	dict

parameters¶

The list of Parameter objects.

Returns:	Parameter list.
Return type:	dict
Default:	[]

property_keys¶

Keys to load as class properties when loading from file.

Returns:	Key names.
Return type:	dict
Default:	['name']

set_value(name, value)¶

Set the value of a parameter by name.

Parameters:	name (str) – Parameter name. value (float) – Parameter value.

class parameters.parameter.Parameter(name, value)¶

Defines a parameter with a name and a value.

Must provide a name and value. Parameters have a generic metadata property stored as a dictionary.

parameter = Parameter('warp speed', 9.0, {'max': 10.0})
parameter.name #=> 'warp speed'
parameter.value #=> 9.0
parameter.meta['max'] #=> 10.0

meta¶

The metadata of this parameter.

Returns:	Parameter metadata.
Return type:	dict
Default:	{}

name¶

The name of this parameter.

Returns:	Parameter name.
Return type:	str

value¶

The value of this parameter.

Returns:	Parameter name.
Return type:	float

Model¶

class model.Model(material=<model.material.Material object>, system=<model.system.System object>, root='')¶

Combines material properties with system parameters.

If, on instantiation, model or system is a string, the associated object will be created from the YAML file, e.g.,

Model('mos2', 'default', 'data')

will load the YAML files at data/mos2.yml and data/default.yml. See parameters.Parameters.load_file().

material¶

The associated Material object.

Returns:	The material.
Return type:	Material

material_parameter(name)¶

Get the value of a material parameter by name.

Parameters:	name (str) – Material name.
Returns:	The value.
Return type:	float

system¶

The associated System object.

Returns:	The system.
Return type:	System

system_parameter(name)¶

Get the value of a system parameter by name.

Parameters:	name (str) – System name.
Returns:	The value.
Return type:	float

class model.Material(path=None)¶

Material specific parameters.

Inherits from parameters.Parameters.

class model.System(path=None)¶

System specific parameters.

Inherits from parameters.Parameters.

Dichalcogenide¶

class dichalcogenide.Dichalcogenide(material=<dichalcogenides.model.material.Material object>, system=<dichalcogenides.model.system.System object>, root='')¶

Model for a dichalcogenide.

Inherits from model.Model.

at¶

Product of the lattice constant and hopping energy.

Returns:	\(at\)
Return type:	float

Δ¶

Valance band conduction band energy splitting.

Returns:	\(Δ\)
Return type:	float

λ¶

Half the valence band spin splitting.

Returns:	\(λ\)
Return type:	float

class dichalcogenide.Energy(dichalcogenide)¶

Dichalcogenide properties related to the energy.

Instantiate with a Dichalcogenide instance, e.g.,

energy = Energy(Dichalcogenide('mos2', 'default'))
energy.e(0, 1, 1, 1)

e(k, n, τ, σ)¶

Band energy.

Parameters:	k (float) – Momentum \(k\). n (int) – Band index \(n = ±1\). τ (int) – Valley index \(τ = ±1\). σ (int) – Spin index \(σ = ±1\).
Returns:	\(E^n_{τ σ} (k)\)
Return type:	float

k(e, n, τ, σ)¶

Inverse energy-momentum relation.

Parameters:	e (float) – Energy \(E\). n (int) – Band index \(n = ±1\). τ (int) – Valley index \(τ = ±1\). σ (int) – Spin index \(σ = ±1\).
Returns:	\(k(E)\)
Return type:	float

class dichalcogenide.UpperValenceBand(dichalcogenide)¶

Dichalcogenide properties related to the upper valence band energy.

For this class, the energy is assumed to be in the upper valence band: \(n = -1\) and \(τ = σ\).

Instantiate with a Dichalcogenide instance, e.g.,

uvb = UpperValenceBand(Dichalcogenide('mos2', 'default'))
uvb.ρ(0)

trig(name)¶

Trigonometric functions of the energy.

• sin θ - \(\sin θ(E)\)
• cos θ - \(\cos θ(E)\)
• sin^2 θ/2 - \(\sin^2 \frac{θ(E)}{2}\)
• cos^2 θ/2 - \(\cos^2 \frac{θ(E)}{2}\)

Parameters:	name (str) – One of the above function names.
Returns:	Corresponding function of the energy \(E\).
Return type:	function

Δμ¶

Chemical potential offset.

The distance of the chemical potential from the top of the upper valence band.

Returns:	\(Δμ\)
Return type:	float
Default:	\(-λ\)

μ¶

Chemical potential.

Determined by the chemical potential offset.

Returns:	\(μ = λ - Δ / 2 + Δμ\)
Return type:	float

ξ_bounds¶

Allowed range for the variable \(ξ = E - μ\).

Returns:	\((\left|Δμ\right| - 2 λ, \left|Δμ\right|)\)
Return type:	tuple

ρ(e)¶

Density of states.

Parameters:	e (float) – Energy \(E\).
Returns:	\(ρ(E) = \left|k'(E) k(E)\right|\)
Return type:	float

class dichalcogenide.Optical(dichalcogenide)¶

Dichalcogenide properties related to optical transitions.

Instantiate with a Dichalcogenide instance, e.g.,

optical = Optical(Dichalcogenide('mos2', 'default'))

p_circular(e, τ, ε)¶

Matrix element for optical transitions (circular polarization): \(\left|P^{+-}_α \left(E, \mathbf{ϵ_±} \right)\right|^2\).

Transitions are from the upper valance band to the lower conduction band. Given in units of \(\text{GeV}^2\).

Parameters:	e (float) – Energy \(E\). τ (int) – Valley index \(τ = ±1\). ϵ (int) – Polarization index \(ϵ = ±1\).

Superconductor¶

class superconductor.Superconductor(model, energy=None)¶

Superconductor.

Uses upper valence band energies by default.

model¶

The model for this superconductor.

Returns:	The model.
Return type:	Model

Δk¶

The superconducting parameter \(Δ_\mathbf{k}\) as a function of the energy \(E\).

Returns:	\(Δ(E)\)
Return type:	func

class superconductor.Induced(model)¶

Induced superconductor.

Inherits from Superconductor.

Δc¶

Conduction band coupling constant.

Returns:	\(Δ_c\)
Return type:	float

Δk¶

The superconducting parameter \(Δ_\mathbf{k}\) as a function of the energy \(E\).

Returns:	\(Δ(E)\)
Return type:	func

Δv¶

Valance band coupling constant.

Returns:	\(Δ_v\)
Return type:	float

About¶