[QE-users] optimization lattice constants of charged single layer 2d metallic materials

[Bin Shao]

Dear all,

I would like to calculate the effect of charge doping on the lattice constant of a 2d metallic material.

According to the manual, we can do this by changing the keywords "tot_charge" to add or remove charges from the neutral system. The excess charge in perfect single layer 2d materials will somehow be delocalized and is compensated by a uniform background opposite charge. But in this case, as I understand, because of the periodic boundary condition, the total energy would depend on the width of the vacuum space. Am I right?

If yes, my second question is if I can do the lattice optimization of charged slab systems by calculating the Energy vs. lattice constant curve with a fixed width of vacuum space.

I also notice that in Quantum Espresso there are two options ("2D" and "esm") for the tag "assume_isolated"  to deal with charged slab calculation. Do I need to switch on this tag? Which option, "2D" or "esm", is the better to serve the purpose?

Any comments and suggestions would be appreciated. Thank you in advance!

Best,
Bin
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