QMol_extField_dipole

External driving field in the dipole approximation

Description

Use QMol_extField_dipole to store the components (electric field, derivative of the electric field, and potential vector) of an external driving field in the dipole approximation. QMol_extField_dipole is a handle class.

Note: QMol_extField_dipole is mainly a container class and it does not check the consistency between the stored electric field, derivative of the electric field, and potential vector. Supplying external-field component that do not match each other will lead to erroneous calculations, e.g., if used in TDSE or TDDFT propagation. For reminder, in the dipole approximation, the electric field and potential vector are related with $E(t)=-\partial_t A(t)$ .

Class properties

External field

The QMol_extField_dipole class defines the following public get-access properties; each can be changed using the set method:

electricField (E)

Electric-field component [ [] (default) | function handle | griddedInterpolant ]

• Function handle should have the following signature @(t) fun(t) and return the value(s) of the electric field at the queried time(s)
• griddedInterpolant enables arbitrary, non-analytic, electric field definition

electricFieldDerivative (DE)

Derivative of the electric-field component [ [] (default) | function handle | griddedInterpolant ]

• Function handle should have the following signature @(t) fun(t) and return the value(s) of the derivative of the electric field at the queried time(s)
• griddedInterpolant enables arbitrary, non-analytic, electric field derivative definition

potentialVector (A)

potential-vectorcomponent [ [] (default) | function handle | griddedInterpolant ]

• Function handle should have the following signature @(t) fun(t) and return the value(s) of the potential vector at the queried time(s)
• griddedInterpolant enables arbitrary, non-analytic, potential vector definition

Other properties

These properties cannot be edited with the set method.

isInitialized (isInit)

Whether the external-field container object is properly initialized. This is used throughout the QMol-grid package to check that the object holds meaningful information and is ready for use. Changing its isSpinPol may cause simulations to fail or produce erroneous results.

Class methods

Creation

constructor

Create an external-field container object with empty class properties.

obj = QMol_extField_dipole;

Create an external-field container object with the name properties set to the specified value. Several name-value pairs can be specified consecutively. Suitable name is any of the external-field properties and is case insensitive.

obj = QMol_extField_dipole(name1,value1);
obj = QMol_extField_dipole(name1,value1,name2,value2,___);

Changing class properties

set

Update the name properties of an external-field container object to the specified value. Several name-value pairs can be specified consecutively. Suitable name is any of the external-field properties and is case insensitive.

obj.set(name1,value1);
obj.set(name1,value1,name2,value2,___);

This is the common name-value pair assignment method used throughout the QMol-grid package. The set method also reset the class. After running, the set property updates the isInitialized flag to false.

reset

Reset the object by deleting/re-initializing all run-time properties of the class and updating the isInitialized flag to false.

obj.reset;

This is the common reset method available to all classes throughout the QMol-grid package.

clear

Clear all class properties

obj.clear;

Clear a specific set of the class properties. Suitable name is any of the external-field properties and is case insensitive.

obj.clear(name1,name2,___);

This is the common clear method available to all classes throughout the QMol-grid package. The clear method also reset the class. The clear method can be used to delete specific properties before saving an instance of the QMol_extField_dipole class.

Initializing the object

initialize

Initialize an external-field container object and sets the isInitialized flag to true.

obj.initialize;

• To avoid any mismatch in internal properties, initialize first reset the object before performing the initialization.
• For compatibility with time propagators, the object can also be initialized using the signature obj.initialize(disc), where disc is a domain-discretization handle

Run-time documentation

getMemoryProfile

Get an estimate of the memory held by a QMol_extField_dipole object with either

mem = obj.getMemoryProfile;
mem = obj.getMemoryProfile(false);

• The estimate only includes external-field components described with a griddedInterpolant and ignores other (small) properties.
• The output mem is the estimated size in bytes.

Additionally display the detail of the memory footprint with

mem = obj.getMemoryProfile(true);

showDocumentation

Display the run-time documentation for the specific configuration of a QMol_extField_dipole object

ref = obj.showDocumentation;

• The output ref is a cell vector containing the list of references to be included in the bibliography.

Examples

Create an external-field container with a -vector and electric-field components

% Potential vector as a function
A  = @(t) cos(0.05*t).*exp(-t.^2/2/1e5);

% Interpolated electric field
t  = -1500:1500;
dt = 1e-5;
E  = -(A(t+.5*dt)-A(t-.5*dt))/dt;
E  = griddedInterpolant(t,E,'pchip','nearest');

% Create external-field container
EF = QMol_extField_dipole('electricField',E,'potentialVector',A);

Display the run-time documentation

EF.showDocumentation;

  * External driving field                            dipole approximation
    Potential vector:          function
    Electric field:            interpolation
    Electric field derivative: N/A
    V-01.21.000 (06/17/2024)                                     F. Mauger

Display the estimated memory footprint

EF.getMemoryProfile(true);

  * External driving field (dipole approx.)                      
    > Electric field                                               46.9 KB

Test suite

Run the test suite for the class in normal or summary mode respectively with

QMol_test.test('extField_dipole');
QMol_test.test('-summary','extField_dipole');

For developers

Other hidden class properties

For compatibility with time propagators, QMol_extField_dipole retains a copy of the domain-discretization handle provided when the object is initialized. It cannot be edited with the set method, nor by any function outside of the object (except for QMol_TDDFT and QMol_TDSE classes). Un-initialized QMol_extField_dipole objects, i.e., isInitialized == false , have hempty disc.

Notes

The results displayed in this documentation page were generated using version 01.21 of the QMol-grid package.

• QMol_extField_dipole was introduced in version 01.10