QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: cherry on July 17, 2009, 16:21

Title: two-probe system optimization
Post by: cherry on July 17, 2009, 16:21

Sorry to bring up this topic again.
I tried to optimize a two-probe system using the methods supplied by ATK/VNL. Although the atomic force is getting smaller and smaller, while the geometry is dramatically distorted (which is not supposed to be). It was suggested that calculating the total energy versus the distance is the best way using ATK/VNL. Is that correct?
Thank you.

Title: Re: two-probe system optimization
Post by: Nordland on July 17, 2009, 18:06

I think you should double check your geometry in VNL?

The best choice of relaxation in ATK is a matter of taste - personally - I prefer to compare the total energy to distances, and I have most experience in doing so.

Title: Re: two-probe system optimization
Post by: cherry on July 17, 2009, 18:23

I did not get the final vnl file since it is not finished yet after hundreds of steps. I plotted the 3-D geometry using matlab, and showing the distortion (one electrode is moving away along x-y plane, assuming z-direction is for current flow.). Does it mean that the optimization methods in ATK are not suitable for two-probe system optimization? Thanks.

Title: Re: two-probe system optimization
Post by: Nordland on July 17, 2009, 23:08

What can be said for sure, is it is a tricky thing to optimize the structure of a twoprobe.

I think something is wrong in your setup, as the electrode atoms are constrained, and can not
be moved. Could you perhaps attach your setup as a script to this post?

Title: Re: two-probe system optimization
Post by: cherry on July 17, 2009, 23:35

Hi Nordland, thanks a lot. Here is the script for a two-probe system.

Title: Re: two-probe system optimization
Post by: cherry on August 5, 2009, 00:35

Is there any script available to compute the relation of total energy versus distance in a two-probe system? Thank you very much.

cherry

Title: Re: two-probe system optimization
Post by: zh on August 5, 2009, 02:54

Quote from: cherry on August  5, 2009, 00:35

Is there any script available to compute the relation of total energy versus distance in a two-probe system?

It's hard to write such a general script for all two-probe systems. One had better do it by himself for his own specific two-probe system.

Title: Re: two-probe system optimization
Post by: Anders Blom on August 7, 2009, 13:03

I believe this has been answered through other channels, right Cherry? :)