QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: gayani2025 on June 25, 2025, 08:44
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Dear All,
Please advice whether this procedure is correct to make unit cell for the geometry optimization.
To prepare the perovskite slab model for geometry optimization in vacuum, I followed a systematic approach using the Surface Cleavage Tool to ensure structural integrity, particularly for the organic component:
Initial Structure:
I started with the experimental bulk crystal structure of the organic–inorganic hybrid perovskite.
Replication:
To avoid the issue of missing surface atoms (especially hydrogen), I first replicated the bulk structure along the c-axis. This ensured a complete molecular unit at the cleaved surface.
Surface Cleavage:
Using the Surface Cleave tool, I created a (001) surface from the replicated structure. This orientation was selected to expose the desired perovskite layer.
Vacuum Addition:
After cleavage, I introduced vacuum spacing on both the top and bottom of the slab to simulate a freestanding perovskite monolayer and eliminate interactions between periodic images.
Layer Isolation:
Finally, I manually removed the excess layers, retaining only a single perovskite unit within the slab. This step ensured that the system represents an isolated slab in vacuum.
⚠️ Note: Direct application of the surface cleavage tool without prior replication caused incomplete surface termination, particularly resulting in missing hydrogen atoms in the organic component. Replication prior to cleavage was therefore essential to obtain a physically realistic and chemically complete slab.
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I have attached the snapshot of the unit cell with out replicating in C direction and do surface cleavage. So some of the H atoms are gone in the structure.
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Sounds reasonable
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Thanks for the message !!!