FleurinpModifier

Description

The FleurinpModifier class has to be used if you want to change anything in a stored FleurinpData. It will store and validate all the changes you wish to do and produce a new FleurinpData node after you are done making changes and apply them.

FleurinpModifier provides a user with methods to change the Fleur input. In principle a user can do everything, since he could prepare a FLEUR input himself and create a FleurinpData object from that input.

Note

In the open provenance model nodes stored in the database cannot be changed (except extras and comments). Therefore, to modify something in a stored inp.xml file one has to create a new FleurinpData which is not stored, modify it and store it again. However, this node would pop into existence unlinked in the database and this would mean we loose the origin from what data it comes from and what was done to it. This is the task of FleurinpModifier.

Usage

To modify an existing FleurinpData, a FleurinpModifier instance has to be initialised staring from the FleurinpData instance. After that, a user should register certain modifications which will be cached and can be previewed. They will be applied on a new FleurinpData object when the freeze method is executed. A code example:

from aiida_fleur.data.fleurinpmodifier import  FleurinpModifier

F = FleurinpData(files=['inp.xml'])
fm = FleurinpModifier(F)                                # Initialise FleurinpModifier class
fm.set_inpchanges({'dos' : True, 'Kmax': 3.9 })         # Add changes
fm.show()                                               # Preview
new_fleurinpdata = fm.freeze()                          # Apply

The figure below illustrates the work of the FleurinpModifier class.

../../_images/fleurinpmodifier.png

User Methods

General methods

  • validate(): Tests if the changes in the given list are validated.

  • freeze(): Applies all the changes in the list, calls modify_fleurinpdata() and returns a new FleurinpData object.

  • changes(): Displays the current list of changes.

  • undo(): Remove the last registered change or all registered changes

  • show(): Applies the modifications and displays/prints the resulting inp.xml file. Does not generate a new FleurinpData object.

Modification registration methods

The registration methods can be separated into three groups. First of all, there are XML methods that require deeper knowledge about the structure of an inp.xml file. All of them require an xpath input:

On the other hand, there are shortcut methods that already know some paths:

  • set_species(): Specific user-friendly method to change species parameters.

  • set_atomgroup(): Specific method to change atom group parameters.

  • set_species_label(): Specific user-friendly method to change a specie of an atom with a certain label.

  • set_atomgroup_label(): Specific method to change atom group parameters of an atom with a certain label.

  • set_inpchanges(): Specific user-friendly method for easy changes of attribute key value type.

  • shift_value(): Specific user-friendly method to shift value of an attribute.

  • shift_value_species_label(): Specific user-friendly method to shift value of an attribute of an atom with a certain label.

  • set_nkpts(): Specific method to set the number of kpoints. (Only for Max4 and earlier)

  • set_kpath(): Specific method to set a kpoint path for bandstructures (Only for Max4 and earlier)

  • set_kpointlist(): Specific method to set the used kpoints via a array of coordinates and weights

  • set_kpointsdata() - User-friendly method used to writes kpoints of a KpointsData node to the inp.xml file. It replaces old kpoints for MaX4 versions and older. for MaX5 and later the kpoints are entered as a new kpoint list

  • switch_kpointset(): Specific method to switch the used kpoint set. (Only for Max5 and later)

  • set_attrib_value(): user-friendly method for setting attributes in the xml file by specifying their name

  • set_first_attrib_value(): user-friendly method for setting the first occurrence of an attribute in the xml file by specifying its name

  • add_number_to_attrib(): user-friendly method for adding to or multiplying values of attributes in the xml file by specifying their name

  • add_number_to_first_attrib(): user-friendly method for adding to or multiplying values of the first occurrence of the attribute in the xml file by specifying their name

  • set_text(): user-friendly method for setting text on xml elements in the xml file by specifying their name

  • set_first_text(): user-friendly method for setting the text on the first occurrence of an xml element in the xml file by specifying its name

  • set_simple_tag(): user-friendly method for creating and setting attributes on simple xml elements (only attributes) in the xml file by specifying its name

  • set_complex_tag(): user-friendly method for creating complex tags in the xml file by specifying its name

  • create_tag(): User-friendly method for inserting a tag in the right place by specifying it’s name

  • delete_tag(): User-friendly method for delete a tag by specifying it’s name

  • delete_att(): User-friendly method for deleting an attribute from a tag by specifying it’s name

  • replace_tag(): User-friendly method for replacing a tag by another by specifying its name

  • set_nmmpmat(): Specific method for initializing or modifying the density matrix file for a LDA+U calculation (details see below)

  • rotate_nmmpmat(): Specific method for rotating a block of the density matrix file for a LDA+U calculation (details see below) in real space

In addition there are methods for manipulating the stored files on the FleurinpData instance directly:

  • set_file(): Set a file on the Fleurinpdata instance

  • del_file(): Delete a file on the Fleurinpdata instance

The figure below shows a comparison between the use of XML and shortcut methods.

../../_images/registration_methods.png

Warning

Deprecated XML modification methods

After the aiida-fleur release 1.1.4 the FleurinpModifier was restructured to enhance it’s capabilities and to make it more robust. During this process several modification functions were renamed or deprecated. Even though all the old usage is still supported it is encouraged to switch to the new method names and behaviours:

Warning

Passing XML Elements to modification functions

Some of the low-level implementations of the XML modification functions accept explicit XML elements as arguments for replacing/inserting. However, these can only be used within limits in the FleurinpModifier at the moment. The reason for this is that there is currently no support for serializing these objects for the input of the Aiida calcfunction. The following functions are affected by this:

Modifying the density matrix for LDA+U calculations

The above mentioned set_nmmpmat() takes a special role in the modification registration methods, as the modifications are not done on the inp.xml file but the density matrix file n_mmp_mat used by Fleur for LDA+U calculations. The resulting density matrix file is stored next to the inp.xml in the new FleurinpData instance produced by calling the freeze() method and will be used as the initial density matrix if a calculation is started from this FleurinpData instance.

The code example below shows how to use this method to add a LDA+U procedure to an atom species and provide an initial guess for the density matrix.

from aiida_fleur.data.fleurinpmodifier import  FleurinpModifier

F = FleurinpData(files=['inp.xml'])
fm = FleurinpModifier(F)                                             # Initialise FleurinpModifier class
fm.set_species('Nd-1', {'ldaU':                                      # Add LDA+U procedure
                       {'l': 3, 'U': 6.76, 'J': 0.76, 'l_amf': 'F'}})
fm.set_nmmpmat('Nd-1', orbital=3, spin=1, occStates=[1,1,1,1,0,0,0]) # Initialize n_mmp_mat file with the states
                                                                     # m = -3 to m = 0 occupied for spin up
                                                                     # spin down is initialized with 0 by default
new_fleurinpdata = fm.freeze()                                       # Apply

Note

The n_mmp_mat file is a simple text file with no knowledge of which density matrix block corresponds to which LDA+U procedure. They are read in the same order as they appear in the inp.xml. For this reason the n_mmp_mat file can become invalid if one adds/removes a LDA+U procedure to the inp.xml after the n_mmp_mat file was initialized. To circumvent these problems always remove any existing n_mmp_mat file from the FleurinpData instance, before adding/removing or modifying the LDA+U configuration. Furthermore the set_nmmpmat() should always be called after any modifications to the LDA+U configuration.