EPW Forum

dear sir.,
the paper which i was working has as follows..
"charge doping is modeled by adding extra electrons and a neutralizing background has bben taken"
please help me how to do these two things i.e, 1. how to add charge 2.and a neutralizing background.

Hi,

Quantum Espresso does if you add 'tot_charge' in the system namelist, From the input description:

By default the unit cell is assumed to be neutral (tot_charge=0).
tot_charge=+1 means one electron missing from the system,
tot_charge=-1 means one additional electron, and so on.

In a periodic calculation a compensating jellium background is
inserted to remove divergences if the cell is not neutral.

dear sir ,
the paper i was referring to states that charge concentration = 2.82 x 10^13 cm-2;
and i was considering intrinsic graphene.
so the value of tot_charge should be??
can u help me how to insert jellium background and the parameters which should be considered..
thank you sir

Hi,

The tot_charge parameter corresponds to the (fractional) number of electrons removed or added in the unit cell, therefore to find the number you want you need to multiply the charge density by the volume (area) of your unit cell.