Author Topic: calculation of capacitance  (Read 2026 times)

0 Members and 1 Guest are viewing this topic.

Offline Sabyasachi Sen

  • Heavy QuantumATK user
  • ***
  • Posts: 52
  • Country: in
  • Reputation: 0
    • View Profile
calculation of capacitance
« on: March 8, 2018, 13:17 »
Recently we have tried to calculate nano-capacitor action in a tow-probe structure. Related Mulliken population, electron difference density, electron difference potential have been calculated. When compared with tutorial given I could not found out the meaning of following terms and how they are calculated, please clarify.
These terms are, net Mulliken charge; is it charge per atom of the electrode part of central region, please clarify.

Accumulated Mulliken charge, meaning not clear. Is the difference between charge on electrode at 0V and finite bias.

Induced charge vs voltage plot, is it the difference in chage per atom of the electrode and molecular part in central region at a given voltage.

please respond at the earliest. From tutorials these issue are not very clear, so please note that.




Offline Jess Wellendorff

  • QuantumATK Staff
  • Supreme QuantumATK Wizard
  • *****
  • Posts: 933
  • Country: dk
  • Reputation: 29
    • View Profile
Re: calculation of capacitance
« Reply #1 on: March 14, 2018, 14:57 »
I agree that the tutorial could explain those details a bit bettoer. - Accumulated Mulliken charge plot: plots the same as the "Net Mulliken Charge" plot above, but in terms of the accumulated Mulliken charge - The induced charge is calculated in this line in the analysis script:
Code
# Compute the total induced charge on one surface, defining the first 7 atoms as belonging to the left surface
q = [-numpy.cumsum(c-net_charges[0])[7] for c in net_charges]
so the induced charge is calculated as CummulativeSum([Q_i]), where Q_i is a list of mulliken charge difference on all atoms in the left part of the central region wrt the zero-bias charge .