Hi,
I am having unstable high temperature phases and I want to calculate free energy of those structures, what is the best and efficient method to calculate it?
I know there are ways to calculate it such as:
Quasi harmonic Debye model, SCAILD method, AIMD method and fast free energy calculations, but I am bit confused which one I should chose?
Every method has some limitations for example, Debye model is kind of analytic, SCAILD and AIMD is too computationally expensive, but no idea about fast free energy. So, under such circumstance, it would be really good if anyone has some experience regarding these methods and can suggest something.
Thanks in advance.
Quasi-harmonic Debye Gruneisen shall be very fast. For this method you may not need to calculate the full phonon spectra. It's probably the first thing to do before trying something more advanced.
Dear Per,
I know you due to Blazej Grabowski who has done some work with you. It's great to hear form you regarding my solution as I know you're one of the most expertise in this field.
May be a short comment: Yes Debye model is quite fast and I got roughly expected results but since (may be) this is not accurate enough/or not exactly ab-initio calculation, we want to calculate something more advanced. But, I am really new in this field so just not sure which one would be good from the advanced methods.
Dear Tanmoy, we have done some work using SCAILD as well. It seems to work well but takes many iterations to converge and is therefore somewhat computationally expensive. We've been looking at the mechanical stabilities (stable phonons) but the free energy is computed as well.
What's the mechanism of that? How does it calculate free energy of an unstable structure?
If you are concerned about computation time, Debye model might be the best choice, although it is not very precise. Otherwise for free energy calculation refer to the following paper
http://www.nature.com/ncomms/2015/150701/ncomms8559/full/ncomms8559.html
I am also working on a toolkit as part of Alloy Theoretic Automated Toolkit (ATAT) that will be released soon.
Thanks Sara for the reference, I will definitely go through it. Since, the question was quite a long time ago so the problem is already solved within the Debye model (you also suggested that).
That is great! I will post my toolkit reference here later, just in case, if anyone need that.
Best of lucks,
Sara
That is great! I will post my toolkit reference here later, just in case, if anyone need that.
Best of lucks,
Sara
Sure! As I also work in random alloys so probably it will help me as well.
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