Creating a convex hull to evaluate a system


#1

Hi
I am sorry if this is a trivial question. I am exploring some systems like BaO-Nb2O5. I could not find calculated structures with relativelly high Nb2O5. So, I have run “Predicted Structures” and now have the probability of many structures and, apparently, the VASP files to calculate the energies.

Is that correct?
Where and how could I run the VASP files to get the energies and construct the “hull”?

Or is there a better way to estimate the lowest energy compounds for each range of compositions?

Many thanks!
Andre


#2

Hi Andre,

That is an excellent start. If we don’t have such structures in our database, there is a good chance we are interested in processing and running calculations on your theoretical structures through our “MPComplete” service.

The way to do this on the website, one at a time for each structure, is to navigate to the Crystal Toolkit app, drag and drop your CIF file to inspect the structure, and then click the Submit Structure button below the structure visual preview. This will allow us to, depending on other internal calculation priorities, run calculations on your structure with our set of VASP input parameters. You can check on the status of submissions from your dashboard on the website.

Alternatively, if you are comfortable with Python programming, you can use this example to submit structures in bulk to us and include optional metadata.

Either way, we will record you as the author of the submission and you will get credited appropriately as having suggested the new structures if they do indeed converge and get added to our public database (with hull energy and all).

Thanks,
Donny


#3

Hi Donny
Many thanks! Wow, this is a fantastic project.
I have now checked the structures for which the VASP files were generated and it seems to me I am in deeper trouble. I am interested in a compound that has a “tetragonal tungsten bronze” structure (P4bm (No. 100)) and has compositions that include the range 25 to 41 mol% BaO. Some of the more “famous” compositions are Ba3 Nb10 O 28 and Ba Nb4 O11. This last stoichiometry is included in the VASP files generated so I am following your advice. I am not sure it was generated as P4bm. I will try to check it,

Meanwhile, I would greatly appreciate your advice again!
Many thanks again
Andre