Timeline for How to deduce phase transitions from a phonon calculation?
Current License: CC BY-SA 4.0
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| Jul 24, 2020 at 9:20 | comment | added | user249 | As long as the structure is not in the ground state you'll keep finding instabilities, so yes, you could do that (although it wouldn't be a very efficient algorithm). Keep in mind that condensing mode by mode is not enough, as phonon-phonon couplings might be important. For instance, for BaTiO3, if you condense the FE mode along two directions onto the cubic structure, you'll notice the new phase is more energetically favorable. The same occurs if you do it along the 3 directions. | |
| Jul 24, 2020 at 7:05 | comment | added | koroma | Thanks for the answer. So if we get to the P4mm structure and I relax it, then I follow this by a phonon calculation, will it still be possible to find new imaginary modes? If so, do I follow the same procedure above multiple times to get a series of symmetry lowering transitions? | |
| Jul 23, 2020 at 12:50 | history | edited | Tyberius♦ | CC BY-SA 4.0 |
minor grammatical changes
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| Jul 23, 2020 at 11:42 | comment | added | user249 | I'm not so familiarized with temperature effects, but I imagine you can find useful the Chochran's soft-mode theory and the Landau Theory of Phase Transitions. Once you generated the potential well, determining the harmonic and anharmonic contributions of a given mode is straightforward. | |
| Jul 23, 2020 at 11:39 | history | answered | user249 | CC BY-SA 4.0 |