QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: tanxj on July 18, 2012, 08:17

Title: Difficult to converge with a large value of charge. NEW!!
Post by: tanxj on July 18, 2012, 08:17
Dear Supreme ATK Wizards:
I want to calculated the transmission for a two-electrode device with the right one charged as described in the inscript. A converged result is obtained if the charge is not too large (such as 0.1).
However, it's very difficult to converge when the charge  is set as large value (in this work, the charge is expected to be 12.0). As discussed in the previous FAQs, the charged system is expected  to use a lot of k-points and a high temperature to reach a convergence. it is confusing that these tips can't work!
I have two doubts about this puzzle.One is that the value of charge must be small compared to the total amount of electrons, the other one is there are some neglectful algorithmic parameters.
Thanks for you attention and I'm looking forward to your replies!

Sincerely,
X. J. Tan
Title: Re: Difficult to converge with a large value of charge. NEW!!
Post by: mads.engelund on July 18, 2012, 09:26
Why do you want to do it?
I'm a little curious because I can't think of a physical system that this would simulate.
Title: Re: Difficult to converge with a large value of charge. NEW!!
Post by: tanxj on July 18, 2012, 09:40
I try to simulate a device with the right electrode consisted of H+ ion instead of H atom.
Why do you want to do it?
I'm a little curious because I can't think of a physical system that this would simulate.
Title: Re: Difficult to converge with a large value of charge. NEW!!
Post by: mads.engelund on July 18, 2012, 10:33
It would certainly be cool if our software could do that!
But with little practical value, since the H+ would attract electrons right away.

We haven't designed for calculating such extreme systems, the changed electrodes are only meant for subtle doping effects. But perhaps it would be worth giving an error message if the value is set too high.
Title: Re: Difficult to converge with a large value of charge. NEW!!
Post by: tanxj on July 18, 2012, 12:15
Got it! Thanks for your help!
It would certainly be cool if our software could do that!
But with little practical value, since the H+ would attract electrons right away.

We haven't designed for calculating such extreme systems, the changed electrodes are only meant for subtle doping effects. But perhaps it would be worth giving an error message if the value is set too high.