[QE-users] 'Tot_charge = x' on surface calculations

[Laurens Siemons]

Dear all,


If I see it the right way, it is fundamentally wrong to use the 'tot_charge' argument from pw.x when performing calculations on surface slabs. Because using the 'tot_charge' argument will introduce a uniform Jellium background over the whole cel. For a surface slab with a vacuum width this means that there will be some charge background in the vacuum as well, which is illogical. Now if you try to run pw.x however on a surface slab (with vacuum), the code will not crash and will come to a result eventually.


My questions:

1) If my thought is right that it is illogical to use 'tot_charge' for surfaces, why doesn't the code crash when you try to do this?

2) Is there any idea how wrong the results are that you obtain by doing calculations this way? For example on first order parameters like energy and second order parameters as chemical shifts?


Kind regards,

Laurens Siemons

Master student University of Antwerp
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