Influence of lack of dielectric constants and Bron charges

[biglinn]

Hi, @mesonepigreco:

When I do SSCHA dyn iterations ensemble generation, calculation of energies and forces, free energy minimization, I give trial dyns from QE ph.x.
So, I have a question.

If trial dyns don't contain dielectric constants and Bron charges(such as, smearing for pw.x that requires epsil = .false. for ph.x), is there any influence?
Since the step ensemble generation will generate supercell, dose lack of dielectric constants and Bron charges lose long-range infomation?

[mesonepigreco]

Long-range effects given by effective charges and dielectric tensors are used only during the Fourier interpolation, which does not happen in a standard calculation. Indeed, to compute the spectral function, you need to perform the interpolation (tutorial 4: https://sscha.eu/Tutorials/tutorial_04_calculation_spectrum/), so in this case, the info about dielectric tensor and Born effective charges are used by the code.