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DFT+U and Hubbard parameter calculation in Quantum Espresso

In this tutorial, we demonstrate how to perform DFT+U calculation, followed by calculation of Hubbard parameters using Quantum Espresso on our web platform.

Create DFT+U workflow

First, we need to create PWscf workflow with DFT+U enabled.

Add pw.x unit

A PWscf calculation (using pw.x) is a prerequisite for the Hubbard parameter (using hp.x) calculation.

  • Navigate to the workflows page from the sidebar and create a new workflow. Expand details section and select Quantum Espresso version 7.2 from the drop-down.

Navigation sidebar

Select application version and build

  • Click Edit button on the default pw_scf workflow unit. Expand the details pane in the unit modal, and select pw_scf_dft_u flavor/ template. Close the unit modal.

Select executable and flavor

Warning

Here we follow the latest DFT+U syntax and method introduced in Quantum Espresso version 7.1. The new template (syntax) pw_scf_dft_u is only available to Quantum Espresso version 7.1 or above. If the user would like to use old syntax, please select Quantum Espresso version 7.0 or below and use pw_scf_dft_u_legacy.

Add hp.x unit to the workflow

Hubbard parameters can be obtained from the first principles. We will use Quantum Espresso hp.x implementation of Linear Response theorem1.

We can add the hp.x workflow to the previous PWscf (DFT+U) workflow by adding a new execution unit. Click the edit unit button on the second unit, and select hp.x executable. The q-grid for hp.x can be modified in the important settings tab.

Add new unit

Tip

We have a bank workflow Hubbard U - HP incorporating above two steps. Navigate to Bank Workflows page via left sidebar and search for Hubbard U - HP workflow, and copy/clone it to your account. Then you may further modify (as necessary) and use it.

Create and submit job

After the above:

  • Navigate to the jobs page via the sidebar menu and create a new job.
  • Select material. Here, we have selected FeO. You can import new material from banks or upload structure files.
  • Select workflow, here, we select the Hubbard workflow that we just created.

Select material and workflow

  • Navigate to Important Settings tab, and scroll down to hubbard section. Here we are able to specify the Hubbard U values specific to atomic species and orbital (Hubbard manifold). You can add new or delete a row in the Hubbard card.

Important settings

Edit Hubbard card

  • Go to Compute tab, and select the number of processors and other compute parameters.

Set compute parameters

Warning

As of 20/Dec/2023, there is a bug in our platform that prevents running MPI jobs in a single processor when the Intel (default) build of Quantum ESPRESSO is used. Please select at least two processors/ cores when using Intel build as a workaround. Alternatively, you may use the GNU build of Quantum ESPRESSO.

Update (18-Feb-2024): The above MPI bug is resolved in platform version 2024.2.15. Now user may run MPI jobs on a single processor when using Intel build of Quantum ESPRESSO.

  • Now, we are ready to submit the job for running the calculation.

Results

Once the job is finished, the Hubbard U values are shown in the Results tab.

Step-by-step screenshare video

In the below animation, we go through an example calculation.

References

  1. HP – A code for the calculation of Hubbard parameters using density-functional perturbation theory, I. Timrov, N. Marzari, M. Cococcioni, Computer Physics Communications, 279, 108455 (2022). ↩