Single Atom Alloys

SAA Figure Single atom alloys (SAA) consist of a transition-metal host with lone dopant atoms embedded at the surface. This dispersion leads to unique electronic properties.

With the autocat.saa module, we can generate structures of these systems to study them further. The main function for this purpose is generate_saa_structures where multiple SAA structures can be generated simultaneously.

>>> from autocat.saa import generate_saa_structures
>>> saa_dict = generate_saa_structures(
...     host_species=["Fe", "Cu"],
...     dopant_species=["Pt", "Au"],
...     facets={"Fe": ["110"], "Cu": ["111"]},
...     n_fixed_layers=2,
...     write_to_disk=True,
... )
Pt1/Fe(bcc110) structure written to ./Fe/Pt/bcc110/substrate/input.traj
Au1/Fe(bcc110) structure written to ./Fe/Au/bcc110/substrate/input.traj
Pt1/Cu(fcc111) structure written to ./Cu/Pt/fcc111/substrate/input.traj
Au1/Cu(fcc111) structure written to ./Cu/Au/fcc111/substrate/input.traj
>>> saa_dict
{'Fe': {'Pt': {'bcc110': {'structure': Atoms(...),
                          'traj_file_path': './Fe/Pt/bcc110/substrate/input.traj'}},
        'Au': {'bcc110': {'structure': Atoms(...),
                          'traj_file_path': './Fe/Au/bcc110/substrate/input.traj'}}},
 'Cu': {'Pt': {'fcc111': {'structure': Atoms(...),
                          'traj_file_path': './Cu/Pt/fcc111/substrate/input.traj'}},
        'Au': {'fcc111': {'structure': Atoms(...),
                          'traj_file_path': './Cu/Au/fcc111/substrate/input.traj'}}}}
Here we generated SAA slabs with Fe and Cu as hosts and Pt and Au dopants under the following conditions:

  • for Fe (Cu) we only need the 110 (111) facet
  • the bottom 2 layers are held fixed

When writing to disk the following directory structure is used: 

.
├── Cu
│   ├── Au
│   │   └── fcc111
│   │       └── substrate
│   │           └── input.traj
│   └── Pt
│       └── fcc111
│           └── substrate
│               └── input.traj
├── Fe
│   ├── Au
│   │   └── bcc110
│   │       └── substrate
│   │           └── input.traj
│   └── Pt
│       └── bcc110
│           └── substrate
│               └── input.traj

N.B. by default, initial magnetic moments are given to the dopant species based upon the ground state magnetic moment of the species