Open BCC · Wide channels
BCC(310)
BCC(310) is a gentler vicinal cut than BCC(210), with broader terrace regions between its raised rows and correspondingly wider channels.
- Plane
- (310)
- Layer character
- Stepped · row-like
- ASE slab builder
surface
From bulk to facet
How BCC(310) is cut
(310)
Moving the normal closer to [100] increases the distance between equivalent ledges. The cut retains BCC's alternating corner/body-centre sequence.
- Bulk lattice
- Body-centred cubic
- Plane normal
- [310]
- What remains
- Wide channels
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.
- terrace ontop1-fold
Above an atom within the terrace.
(u,v) = (2/5, 1/2)s = s₁ · support shell: mean Δz = -1.815 Å from L1Projection of the L3 atom at (2/5, 1/2).
Not named in ASE - raised-row ontop1-fold
Above an atom on the raised row.
(u,v) = (3/10, 0)s = s₁ · support shell: mean Δz = +0.000 Å from L1Projection of the L1 atom at (3/10, 0).
Not named in ASE - lower-row ontop1-fold
Above an exposed atom in the lower row.
(u,v) = (1/10, 1/2)s = s₁ · support shell: mean Δz = -0.908 Å from L1Projection of the L2 atom at (1/10, 1/2).
Not named in ASE - row bridge2-fold
Between neighbours along the raised row.
(u,v) = (3/10, 1/2)s = (s₁ + s₂) / 2 · support shell: mean Δz = +0.000 Å from L1Periodic midpoint of L1 (3/10, 0) and L1 (3/10, -1).
Not named in ASE - terrace bridge2-fold
Between adjacent atoms within the terrace.
(u,v) = (1/10, 0)s = (s₁ + s₂) / 2 · support shell: mean Δz = -0.908 Å from L1Periodic midpoint of L2 (1/10, 1/2) and L2 (1/10, -1/2).
Not named in ASE - cross-row bridge2-fold
Between atoms in raised and lower rows.
(u,v) = (1/5, 1/4)s = (s₁ + s₂) / 2 · support shell: mean Δz = -0.454 Å from L1Periodic midpoint of L1 (3/10, -1) and L2 (1/10, -1/2).
Not named in ASE - channel fourfold pocket4-fold
In the mixed-height channel between rows.
(u,v) = (9/20, 1/2)s = (Σᵢ sᵢ) / 4 · support shell: mean Δz = -0.454 Å from L1Least-squares centroid of the 4-atom projected shell: L1 (3/10, 0), L1 (3/10, -1), L2 (3/5, 0), L2 (3/5, -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
Comparing (210) and (310) directly shows how a smaller miscut increases terrace width without changing the basic ledge direction.
Cell
Geometry at a glance
Here \(d_{310}=a/\sqrt{10}\), and [310] is \(\cos^{-1}(3/\sqrt{10})\approx18.4^\circ\) from [100].
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.build import bulk, surface
fe = bulk("Fe", "bcc", a=2.87, cubic=True)
slab = surface(fe, (3, 1, 0), 10, vacuum=10)
Things that are easy to misread
- Interchanging the row and cross-row directions.
- Comparing coverages without accounting for its larger surface cell.