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I am performing ferroelectric calculations for 2D Sb-doped Bi2Te3, which is a topological insulator with an energy gap of approximately 70 meV, using VASP. What should my INCAR file contain for an accurate ferroelectricity study? Are there specific flags or settings I should consider for polarization calculations and Berry phase analysis?

Hi,

By setting LCALCPOL=True, VASP performs the Berry-phase calculation already on all spatial directions. That means, in principle, you don't need any extra INCAR tags.

As with every VASP calculation, however, you should ensure that your results are properly converged. That means at the very least

• Converging with respect to ENCUT

• Converging with respect to the number of k-points in the KPOINTS file

• You may want to set PREC=accurate

• Converging with respect to cell size or number of atoms

• Make sure that you choose an appropriate ISMEAR and SIGMA

These are some of the basic suggestions that ensure a base level of accuracy in most VASP calculations. I hope that I was able to help you with your question.