Dear L, Thanks for your clear explanation, I understand it now. Best Regards, HY Lu
在 2023年11月15日 星期三 下午06:06:21 [GMT+8], Lorenzo Paulatto<lorenzo.paula...@cnrs.fr> 寫道: Sorry but for 1 more naive question, if I use 2 unit cell instead of 1 in DFPT, would it be expected to have difference between the two cases ( only at Gamma point) ? yes, it is different. Because you would get twice as many phonons, but half of them would be periodic inside the supercell (and correspond to Gamma) the other would not be (and correspond to a zone-border q-point). hth Best Regards, HY Lu 在 2023年11月15日 星期三 下午03:56:04 [GMT+8], Lorenzo Paulatto<lorenzo.paula...@cnrs.fr> 寫道: _______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users On 15/11/2023 08:45, ludwigboltzmann.s...@nycu.edu.tw wrote: Hope this will give you an idea why such symmetry reduced supercell calculation is being carried out. The idea is "symmetry reduced". I.e. DFPT allows you to simulate a monochromatic perturbation of any periodicity with a unit cell, while frozen phonon can only simulate perturbation which have the periodicity of the cell you are using. But to break symmetry, you need a supercell. kind regards L _______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users -- Dr. Lorenzo Paulatto IdR @ IMPMC - CNRS UMR 7590 & Sorbonne Université phone: +33 (0)1 442 79822 / skype: paulatz http://www.impmc.upmc.fr/~paulatto/ - https://anharmonic.github.io/ 23-24/423 B115, 4 place Jussieu 75252 Paris CX 05 _______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users