Is anyone else struggling with VASP convergence on perovskite surfaces?
I am running slab relaxations for mixed-halide perovskites and keep hitting charge sloshing when vacuum exceeds 18 A. I tried reducing mixing amplitude and switching between ALGO = Normal and ALGO = Fast, but ionic steps still oscillate. K-point density is moderate (4x4x1), ENCUT is 1.3x ENMAX, and I include dipole correction.
Has anyone found a stable recipe for these systems, especially when spin-orbit coupling is enabled? I can converge bulk cells reliably, but slab geometries with defects are painful. Any tips on pre-relaxation strategies or good default mixing parameters would save me days of queue time.
Posting as Anonymous Researcher
Comments
Try starting with a lower ENCUT pre-relaxation and tighter mixing only after forces drop below 0.2 eV/A. That often damps the initial charge oscillation.
For halide systems, Kerker mixing with a slightly larger AMIX can help if vacuum is large. Also check whether your dipole direction matches slab orientation.