Dear Chris, I do not know what the origin of your problem may be. What I can say is that it is probably not a good idea to run such a relatively large computation just to evaluate the vibrational properties of a thin metal layer. A smarter approach would probably be to compute interatomic force constants using a thinner slab (the range of the force constants is likely 2-3 bond lengths in Cu), and than to use the ab initio force constant to build a model for a slab of any thickness … By the way the size of the vacuum region is likely also an overkill …
SB > On 6 Nov 2018, at 14:31, Christoph Wolf <[email protected]> wrote: > > Dear all, > > I am trying to calculate the phonon spectrum for a series of thin metal > layer. However there seem to be a few "pathological" cases such as Cu(111) > where, no matter what, I cannot achieve convergence during the ph.x > calculation. > > I have tried, to no avail, change mixing parameter, k point sampling, > ecutrho, ecutwfc, smearing type, occupation type, ... > > If someone has a hint on how to tackle this I would be entirely grateful. I > know it can be done as there are a few works out there focusing on thin metal > film phonons but non of them has additional information. > > The general setup is 11 layers of metal padded by 20A of vacuum. I generated > the layers using "thermo_pw" and I manually and meticulously checked bond > lengths and residual forces on the atoms after relaxation (<1e-6). > > Any help is very welcome! > > Thanks in advance and with best regards, > Chris > > -- > Postdoctoral Researcher > Center for Quantum Nanoscience, Institute for Basic Science > Ewha Womans University, Seoul, South Korea > _______________________________________________ > users mailing list > [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users — Stefano Baroni - Trieste — http://stefano.baroni.me <http://stefano.baroni.me/>
_______________________________________________ users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
