Procedure: prepare a two-dimensional slab

Geometry prerequisites

• Start from a physically meaningful termination, composition, and surface orientation.
• Inspect fractional and Cartesian coordinates. A tilted cell needs vacuum measured normal to the surface, not merely the length of c.
• Check that the slab has the intended thickness and no unintended cross-boundary bonds.
• Duplicate the structure before changing the cell so the original bulk or slab remains available.

Prepare the model

1. Orient the surface in the a-b plane. Verify the lattice-vector geometry instead of relying only on camera orientation.
2. Set cell repetition along c to 1 (e.g. 2 × 2 × 1) to inspect the in-plane extended surface without repeating along the vacuum direction.
3. Use the explicit vacuum action for the a-b surface. Inspect the updated cell and confirm interatomic Cartesian distances remain appropriate.
4. Choose an in-plane mesh N × M × 1, with N and M established by convergence.
5. Review the electrostatic treatment in the generated or expert QE input. Asymmetric, polar, and charged slabs need specific consideration.
6. Converge slab thickness, vacuum, and in-plane sampling against the quantity of interest.

Understand a strained slab

Biaxial in-plane strain modifies the in-plane metric. Record the strain tensor, reference lattice, and whether atoms are relaxed at fixed in-plane cell.

Changing vacuum height changes the three-dimensional cell volume without changing the physical sheet thickness. A reported stress or conductivity normalized by this arbitrary volume may require a clearly defined two-dimensional conversion.

The c-vacuum helper does not construct every wire, arbitrary Miller-index slab, or isolated cluster. Import or prepare the appropriate geometry when the required operation is outside the builder tools.

Validate before submission

Related topics

• Import and inspect a structure
• Edit atoms and cell geometry
• Periodic directions, vacuum, and dimensionality