I am trying to model a metal oxide system with an adsorbate in Quantum Espresso with the Environ module. For this, I am following an example from the module itself, example04 which
shows how to use pw.x to model 2D periodic systems in contact with a continuum solvent. (from README file)
The file further goes on to state that:
Note that the keyword solvent_mode='full' is mandatory in this calculation, in order to remove the artifact of the Pt valence density, which presents a hole close to the position of ion, due to the missing core electrons. In order to avoid the continuum solvent to enter such a hole, a quickly vanishing gaussian density is added at the position of the nuclei when defining the dielectric. The same problem is likely to occur in halogens and other transition metals.
Can anyone give some idea as to what this artifact is in the Pt valence density, the hole close to the ion, and missing core electrons are?
(The pseudopotentials used in the example are: O.pbe-rrkjus.UPF C.pbe-rrkjus.UPF Pt.pbe-nd-rrkjus.UPF)
Any insights would be greatly appreciated.