Prismatic BCT · Centred rectangular net
BCT(110)
BCT(110) contains both corner and body-centred sites in each atom-bearing plane. The centred rectangle supports diagonal, basal-channel, and axial-row bridge geometries.
- Plane
- (110)
- Layer character
- Prism · dense rows
- ASE slab builder
surface
From bulk to facet
How BCT(110) is cut
(110)
The plane bisects the two basal axes equally and remains parallel to c; the body-centred site lies in the same member of the plane family as corner sites.
- Bulk lattice
- Body-centred tetragonal
- Plane normal
- reciprocal vector G(110)
- What remains
- Centred rectangular net
The plane is drawn through the centre so high-index cuts remain legible. Its orientation is what the indices specify, not its absolute position inside one cell.
Surface geometry
Read the surface from above
L1 is the highest atom-bearing plane, followed by L2 and L3. Support coordinates outside 0–1 are periodic images. The listed Δz describes the supporting atoms, not the marker height. In the interactive model, every numbered site is placed on the same schematic guide plane above the slab; no adsorption distance or energetic ordering is implied.
- ontop1-fold
Above one atom of the centred outermost net.
(u,v) = (1/2, 0)s = s₁ · support shell: mean Δz = +0.000 Å from L1Projection of the L1 atom at (1/2, 0).
Not named in ASE - diagonal bridge2-fold
Between the two staggered sublattices in the surface plane.
(u,v) = (1/4, 1/4)s = (s₁ + s₂) / 2 · support shell: mean Δz = +0.000 Å from L1Periodic midpoint of L1 (1/2, 0) and L1 (0, 1/2).
Not named in ASE - basal bridge / fourfold channel4-fold
The basal midpoint also occupies the centre of the four-atom channel
(u,v) = (0, 0)s = (s₁ + s₂) / 2 · support shell: mean Δz = +0.000 Å from L1Periodic midpoint of L1 (1/2, 0) and L1 (3/2, 0).
Not named in ASE - axial-row bridge2-fold
Between equivalent atoms parallel to c.
(u,v) = (1/2, 1/2)s = (s₁ + s₂) / 2 · support shell: mean Δz = +0.000 Å from L1Periodic midpoint of L1 (1/2, 0) and L1 (1/2, 1).
Not named in ASE
Interactive model
Rotate the slab
Sites share a schematic display height · drag to rotate · hover for names
Below the top layer
Why the sites are different
Each layer contains two staggered rows. Their separations depend on c/a, so a square-looking projection should not be assumed without checking the metric.
Cell
Geometry at a glance
The spacing is \(d_{110}=a/\sqrt{2}\). A conventional surface rectangle has sides \(a\sqrt{2}\) and \(c\) and contains two lattice sites.
A site name describes the ideal starting geometry. Relaxation can move an adsorbate away from it.
Practical model
Build it with ASE
The builder creates the slab. Sites marked ASE keyword can be passed directly as a named position; ASE source marks current but inconsistently documented support. Other sites require explicit Cartesian coordinates converted from the fractional construction above.
from ase import Atoms
from ase.build import surface
a, c = 3.25, 4.95
indium = Atoms("In2", scaled_positions=[(0, 0, 0), (.5, .5, .5)],
cell=[(a, 0, 0), (0, a, 0), (0, 0, c)], pbc=True)
slab = surface(indium, (1, 1, 0), 8, vacuum=10)
Things that are easy to misread
- Reducing every bridge to the cubic BCC(110) labels without considering c/a.
- Counting the two staggered outermost rows as different atomic layers.