A simple question: did you relax your slabs? On Fri, Apr 6, 2018 at 9:57 AM, Christoph Wolf <[email protected]> wrote:
> Dear all, > > I am curious if someone could shed some light onto the following: > > I am currently calculating phonons of MgO using QE 6.2.1 and NC PPs from > the ONCV library (requirement of post-processing with YAMBO). Bulk > properties (lattice and vibrational) are very nicely reproduced. > > When moving to slabs (1,2,3 layers with ca 20 A vacuum, dipfield > correction applied) phonons become considerably "ugly" (very high energy > imaginary modes). I was wondering if there is a "trick" to get better > phonons in slabs with polar surfaces either during ph.x (I tried tighter > convergence down to 10e-16, higher k grids in pw.x, higher q grids in ph.x > without much success) or post-processing (not sure if the usual ASR are > applicable in slabs)? > > Since calculations on the slabs are rather time consuming any suggestion > is very welcome! > > A nice weekend to everyone from San Sebastian, > > 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 > -- ******************************************************* Ilya Ryabinkin Postdoctoral Scholar Physical and Environmental Sciences University of Toronto Scarborough http://www.utsc.utoronto.ca/~aizmaylov/Members.html *******************************************************
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