QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: yasheng on February 8, 2016, 13:25

Title: Charged system
Post by: yasheng on February 8, 2016, 13:25

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
 

Title: Re: Charged system
Post by: Jess Wellendorff on February 9, 2016, 11:31

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.

Title: Re: Charged system
Post by: yasheng on February 9, 2016, 16:21

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.

Title: Re: Charged system
Post by: Jess Wellendorff on February 10, 2016, 08:40

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