ElectricFieldConstraint support for BaTiO3 structure

[Sandhiya]

Hello,

Please help with how to apply an external electric field to the BaTiO₃ unit cell structure using a Hybrid (HSE06) function in QuantumATK. I used the ElectricfieldConstraint property for applying a certain voltage on the Z-axis of the BaTiO₃ unit cell. Still, its bandgap and density of states do not change remain the same as the optimized unit cell value. Please find the attachment below and whatelse needs to be modified to work. What parameters should be used when applying an external electric field to the BaTiO3 unit cell structure?
Another way to work on the external electric field on the BaTiO3 unit cell structure. Please reply someone.

Thanks

[AsifShah]

I faced somewhat similar issue with MoS2. Even under high electric field, the atoms barely move than expected. Just leaving this comment to follow-up on response from QATK.

[Anders Blom]

First of all, I would make sure you have a working setup for GGA, before trying this extremely time-consuming calculation with HSE. Also, use the update strategy "FixElectricFieldCorrection" to avoid recalculating the Born charges each time, before you have a working methodology. This is just to make sure the principle of the calculation works. Now, note that 10000 V/cm is actually not a large field, it corresponds to 1 mV applied over 1 nm (typical unit cell size, roughly), so that might explain what you both observed.