Gate voltage calculations in ATK

[kanna]

Dear QuantumWise Staff,

Can you please provide more details about how three terminal calculations are done in ATK ?
Is this published or documented somewhere ?

Thanks
Kanna

[Jess Wellendorff]

When you say "three terminal calculations", do you then mean simulating a real three-terminal device (where current flows between 3 electrodes), or do you mean two-terminal calculations with a gate in the middle? The first option is currently not possible with ATK. In the latter case, the gate simply implies a constant electrostatic potential in the region of space occupied by the gate.

[kanna]

I meant gate in the middle, yes, I was talking about the effect of gate as an electrostatic source.
Can you please provide me some details as I need to use it for some analysis ?
I want to know how exactly the hamiltonian is modified, in particular, how the position of the gate influences the current ?

Thanks
kanna

[Jess Wellendorff]

The gate potential enters the effective potential in the Hamiltonian as an "external electrostatic field":
http://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/chap.atkdft.html
This external potential is constant in the region of space occupied by the gate material, and then decays into the rest of the simulation cell just like any other field in the Hamiltonian.