Dielectric and Born effective charge tensors with electric enthalpy approach

Hello everyone,

I found some discrepancies between the calculation of the Born effective charge and the dielectric tensors with DFPT and with the (finite-difference) electric enthalpy approach. More precisely, I found the following results (reported in the table) for the system CoO, MgO and PbTiO3 (the number in parentheses are the reference values, which references are reported below). I don't manage to reproduce the results in [2].

Table.pdf

I also made cutoff and k-point convergence tests, but the results are the same, in particular for the effective charges.

In the file attached you can also find the input files for the calculations.

Inputs.zip

Does someone has any opinions about this issue? Thanks in advance.

Best - Luca Binci

[1] A. Floris, I. Timrov, B. Himmetoglu, N. Marzari, S. de Gironcoli, M. Cococcioni, Phys. Rev. B, 101, 064305 (2020).

[2] P. Umari and A. Pasquarello, Phys. Rev. Lett. 89, 157602 (2002).

[3] W. Zhong, R.D. King-Smith and D. Vanderbilt, Phys. Rev. Lett. 72, 3618 (1994).

[4] Same calculation (same input file), but with DFPT.