Author Topic: Mobility calculation on graphene  (Read 122 times)

0 Members and 1 Guest are viewing this topic.

Offline paramjot

  • Regular ATK user
  • **
  • Posts: 20
  • Country: ca
  • Reputation: 0
    • View Profile
Mobility calculation on graphene
« on: June 22, 2020, 23:55 »
Hi! I calculating doped graphene mobility using the tutorial in the website using dell precision 5720 of 1 tb RAM but it still takes 14 days to compute the result. is there any faster way to do so?

Offline Tue Gunst

  • Regular ATK user
  • **
  • Posts: 12
  • Country: dk
  • Reputation: 0
    • View Profile
Re: Mobility calculation on graphene
« Reply #1 on: June 23, 2020, 09:43 »
Hi,
So guess you are following this recently updated tutorial:
https://docs.quantumatk.com/tutorials/mobility/mobility.html

The time-limiting step is the full (k,q)-dependent electron-phonon coupling (EPC). If this is not the case then please state where you are waiting.
It should take approximately 10 hours on a 16-core node to do the EPC in the tutorial.
If that is not the case then maybe check again that all the settings are as in the tutorial.

In general, the EPC can be parallelized over many processes (as there are many combinations of k and q-points).
The following Mobility calculations can be done on a single core and only takes a few minutes.

Offline paramjot

  • Regular ATK user
  • **
  • Posts: 20
  • Country: ca
  • Reputation: 0
    • View Profile
Re: Mobility calculation on graphene
« Reply #2 on: June 23, 2020, 13:24 »
I use GGA for the calculation and the sampling format of EPC is not the same in my quantum atk software. so I use 3x3x1(i have attached the pics of my EPC sampling format and example's one) graph has 25 atoms. EPC and Hamiltonian matrix take the most of the time like around 13days. I use the isotropic scattering rate method

Offline Roc2019

  • Regular ATK user
  • **
  • Posts: 29
  • Country: cn
  • Reputation: 0
    • View Profile
Re: Mobility calculation on graphene
« Reply #3 on: June 25, 2020, 02:22 »
Dear Dr. Gunst ,

Is it possible to calculate the mobility of a spin-polarized structure, such as a 2D magnetic monolayer?

Thank you.

Offline Tue Gunst

  • Regular ATK user
  • **
  • Posts: 12
  • Country: dk
  • Reputation: 0
    • View Profile
Re: Mobility calculation on graphene
« Reply #4 on: June 25, 2020, 10:49 »
@paramjot:
It seems from your example that you only include 1 k and q point? Do I understand correctly that you try to do a calculation not for the primitive cell but a large graphene unitcell?
Parallelization will only help if you have k and q points.

@Roc2019:
Yes, it will work for polarized calculations. You can also do the spin life-time (check the ElectronPhononCoupling object description in the reference manual if interested).

Offline Roc2019

  • Regular ATK user
  • **
  • Posts: 29
  • Country: cn
  • Reputation: 0
    • View Profile
Re: Mobility calculation on graphene
« Reply #5 on: June 25, 2020, 13:06 »
Thank you Dr. Gunst .

Offline Roc2019

  • Regular ATK user
  • **
  • Posts: 29
  • Country: cn
  • Reputation: 0
    • View Profile
Re: Mobility calculation on graphene
« Reply #6 on: June 28, 2020, 05:41 »
Dear Dr. Gunst,

As I follow the new mobility example by 2019.12.sp1, I get the same mobility result.  But,  it prints the error infomation as analyzing the EPC.  So, what's wrong?  How to get the EPC picture in specified qx-qy palne?

Thank you.