Query related to piezoelectric calculation

[harkishan_dua]

I think piezoelectric analysis in quantumATK is implemented for 3D material. Can you please suggest me how to calculate it for a 2D material using quantumATK?

[Anders Blom]

It works just the same way, except you don't need any k-points in the non-periodic direction. QuantumATK, like most codes, treats 2D materials as 3D as well, just with a large vacuum region between each sheet to avoid electrostatic or direct interactions.

[harkishan_dua]

Ya I have kept large vacuum region along the non periodic direction. However, the calculated coefficient for a 2D material are in the units of C/m^2 whereas  the coefficient for a 2D material are in the units of C/m.

[Anders Blom]

Well, only in theory, if you assume the 2D layer to infinitesimally thin. You will still see reported measured values given in C/m^2 (such as in https://www.nature.com/articles/s41699-018-0063-5). To convert to a pure 2D quantity you could multiply by the physical thickness of the 2D layer, but this is hard to estimate.