Author Topic: how to display dumbbells through W-S defect analysis  (Read 73 times)

zeroz

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how to display dumbbells through W-S defect analysis
« on: December 28, 2017, 09:06:30 AM »
Hi,all:
I want to use W-S defect analysis modifier to do point defect analysis,but as mentioned in manual,once the W-S analysis is performed,the reference configuration will replace the original
displaced configuration,and Interstitial positions(Occupancy==2) display as sphere instead of a dumbbell structure or a interstitial.

How can I show accurate sturcture in interstitial positons(such as dumbells toward different directions)  rather than the rough sphere?
Thank you very much.

Xtof

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Re: how to display dumbbells through W-S defect analysis
« Reply #1 on: December 28, 2017, 05:19:25 PM »
Interesting question. I would also be interested in knowing how to do that.

Best regards,
Christophe

Alexander Stukowski

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Re: how to display dumbbells through W-S defect analysis
« Reply #2 on: January 04, 2018, 04:56:44 PM »
Yes, I agree, this is an interesting question  :) I do not see that the current version of OVITO provides a solution to this problem, which others have been facing before.

Basically, the W-S modifier needs to be extended (requiring code modifications). Here is what I have in mind: We could add an option that turns off the normal behavior of the W-S modifier: Instead of replacing the current configuration with the reference configuration, the current configuration is kept. The occupancy numbers that are assigned to the individual atoms then represent the total occupancy of the sites the atoms have been assigned to. The two atoms forming a dumbbell configuration, for example, would both have Occupancy==2. Of course, in this mode it would not be possible to select vacancies, because there are no atoms occupying vacancy sites. Also, the "Output per-type occupancies" option would not make any sense in this mode.

What do you think?

In principle, it is possible to implement this algorithm using a custom "Wigner-Seitz" modifier written in Python. So if you have an urgent need for this approach, that would be the way to go. Otherwise, let me create an issue for this feature request on our GitLab site and I will try to extend the built-in W-S modifier when I find some time.