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Components

We present in this page the components (executables and flavors) of the Quantum 3xplorer (Q3) application implemented on our platform. They can be inspected from the lists of available executables and flavors under the Unit Editor Interface.

Implementation on our platform

The user who wishes for additional functionality to be added to our platform in future should express so via a support request.

Executables

The platform provides a single executable, q3, which runs the MPI-parallel build of the engine. The input file is passed to it as the only positional argument.

Flavors

The q3 executable allows for the following calculation flavor.

The properties extracted from the output of q3_scf are the total energy and the Fermi energy.

Input Files

The q3_scf flavor uses two input files. The first one, material.json, holds the material in its structured representation. The template of this file is filled from the job context: the workflow fetches the material of the job from the platform and assigns it to the MATERIAL variable, which is written to material.json at runtime.

The content of material.json can also be overwritten with complete material data, for example in the Unit Editor or in a command-line job. Material data in this format is available from the Standata repository (@mat3ra/standata). Structures from the Materials Project database can be imported into the platform first, which stores them in the same format.

The second input file, q3_scf.yml, is the Q3 input in YAML format, which refers to material.json and sets the method, the self-consistent field parameters, and the output location.

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material: material.json

method:
  type: pseudopotential
  subtype: ultrasoft

  pseudopotentials:
{%- for specie in input.ATOMIC_SPECIES %}
    {{ specie.X }}: {{ specie.PseudoPot_X }}
{%- endfor %}

  cutoffs:
    wavefunction: {{ cutoffs.wavefunction }}
    density: {{ cutoffs.density }}

  scf:
    convergence_threshold: 1.0e-9
    max_iterations: 100

    smearing:
      type: gaussian
      degauss: 0.02

    mixing:
      beta: 0.3
      mode: broyden

    kgrid:
      dimensions: [{{ kgrid.dimensions | join(', ') }}]
      shifts: [{{ kgrid.shifts | join(', ') }}]

control:
  calculation: scf
  prefix: q3
  outdir: ./outdir/

The input is a template rendered at job submission. The pseudopotential files are resolved from the elements of the material, the plane-wave cutoffs (in Rydberg) from the method parameters, and the k-point grid from the unit settings.

Examples

Two sets of ready-to-run inputs are available for Q3.

  • The q3/scf example of the CLI job examples repository contains a batch script, the Q3 input, and the material file for a self-consistent field calculation of FCC silicon, the same system as the Quantum ESPRESSO pw.x example. On the compute clusters, the example is located under ~/job_script_templates/q3/scf and can be submitted as explained in the command-line jobs documentation.
  • The examples directory of the Q3 source repository covers the total energy of semiconductors, metals, magnetic metals, and isolated atoms, as well as band structures (including Wannier interpolation), densities of states, and relaxations.