Charged system

[yasheng]

Dear All,

I am a new user of Quantumwise, and I have some questions about charged system. I saw some posts about charged system in this forum, but it is not very clear for me how exactly to do it.

(1) first of all, where we can see the number of electrons in the system?

(2) if we want add charge q=-1, or q=+1 to the system, how do we do it?

Thank you,
Yasheng
 

[Jess Wellendorff]

1) The total number of electrons is the sum of density matrix contributions, called "DM" in the ATK log file: "Density Matrix Report                          DM        DD "

2) You can set the charge in the "Basic" tab on the Script Generator, see attached PNG.

[yasheng]

Thank you.

What is the difference between defining charge on the scripter and the method mentioned in the following tutorial?

http://quantumwise.com/publications/tutorials/item/820-ni-silicide-si-interfaces

# -------------------------------------------------------------
# Add Doping
# -------------------------------------------------------------
doping_density = 1e+20
# Calculate the volume  and convert it to cm^-3
volume = right_electrode_lattice.unitCellVolume()
volume = float(volume/(0.01*Meter)**3)
# Calculate charge per atom
n_doping = doping_density * volume / len(right_electrode_elements)
# Add external potential to the central region
external_potential = AtomicCompensationCharge([
        ('doping_central_region', n_doping)
        ])
 
central_region.setExternalPotential(external_potential)
# Dope the right electrode
right_electrode.setExternalPotential(
      AtomicCompensationCharge([(Silicon, n_doping)]))


In both methods, we add charge in different ways.

[Jess Wellendorff]

As explained in the ATK Reference Manual, http://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/ref.atomiccompensationcharge.html, AtomicCompensationCharge is mainly used for adding a uniform doping to semiconductors.