Dear all, I am working on hydrogen trapping in a tungsten vacancy. * I first create a vacancy in a 3x3x3 supercell that I optimize, * Then I trap a H atom inside, then I relax the system, * I further need to know the phonon frequencies of the hydrogen atom to compute thermodynamic properties. Due to the mass difference between H and W, the phonon modes associated to H are assumed to be decoupled from the W ones. So the only H phonon modes are calculated at the gamma point.
My question is about dynmat.x. Should I use it or not ? As recommended in the phonon tutorial file (http://www.quantum-espresso.org/wp-content/uploads/2013/06/phonons_tutorial _shanghai1.pdf) I run dynmat.x routine after the phonon calculation. Dynamt.x is designed to impose the acoustic sum rule to the acoustic modes. But in my case there are no acoustic modes since all the W atoms are fixed. The problem is that H frequencies look like very different with and without dynmat.x. So my question, what are the correct ones ? I attach below: The inputs w3_vac_HOh_ph.in w3_vac_HOh_dynmat.in and outputs w3_vac_HOh_ph.out, w3_vac_HOh_dynmat.out of the phonon calculation. Many thank you for your help ==================================================================== Nicolas Fernandez, PhD student Equipe de Spectrométrie et Dynamique Moléculaire Laboratoire de Physique des Interaction Ioniques et Moléculaire (PIIM) UMR-CNRS 7345, Aix Marseille Université Campus de St Jérôme, Service 252 13397 Marseille Cedex 20
w3_vac_HOh_dynmat.out
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w3_vac_HOh_dynmat.in
Description: Binary data
w3_vac_HOh_ph.out
Description: Binary data
w3_vac_HOh_ph.in
Description: Binary data
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