Up to what stresses can PBE / R2SCAN results be trusted?

[matthewkuner]

As a general rule (i.e. for applying to most/all of the periodic table), above what stress does the frozen core approximation start to significantly affect the accuracy of a VASP calculation? Does this depend on the external pressure, or individual components of the stress tensor? And I assume that this only noteworthy for high pressures (i.e. highly compressed systems)--let me know if that assumption is incorrect. Thanks in advance!

[jonathan_lahnsteiner2]

Dear matthewkuner,

This question cannot be answered in general because the answer will strongly depend on the material under consideration. You could compare your vasp PAW results to an all-electron calculation to be sure that the frozen core approximation is still applicable under the stress of interest.

You are right in your assumption that the applicability of the frozen core approximation will depend on the external pressure since it will decrease the volume of your simulation box. The applied external pressure will also influence the individual components of the stress tensor. And yes this will only be noteworthy for high external pressures.

Maybe there will be some user in the user-for-users forum who has more insight into this topic.

All the best

Jonathan