Hello,everyone!
There is a paragraph in a paper:
The search for the ground state was started with the determination of the structure for which frequencies of all optical phonons at the Γ point would be positive. Since in the phonon spectrum of the P4/mmm phase of all the investigated superlattices, there were unstable modes at the Γ point (with imaginary mode frequencies), small perturbations corresponding to the eigenvector of the least stable of these modes were introduced into the structure and the fequilibrium structure of the low symmetry phase was
determined by means of the relaxation of atomic positions and the unit cell parameters.
So I calculate the dynamical matrix at Gamma point with BTO.in, then anaddb the DDB file with input file btogamma.in. I got some eigendisplacements corresponding to different modes, as in btogamma.out. Is the eigendisplacement the very perturbation to be introduced to the structure? If not, how can I realise the search described in the paper! Thank you!
Input files are attached.
Finding ground state with optical phonons
Moderator: bguster
Finding ground state with optical phonons
- Attachments
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BTO.in- (1.38 KiB) Downloaded 183 times
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- btogamma.in
- (147 Bytes) Downloaded 182 times
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- btogamma.out
- (3.61 KiB) Downloaded 171 times