Dear all, I am curious if this is a common problem: when calculating the phonons of an insulator and a metal I face no problems in slab geometry. But when both are put together there will always be a q-point where convergence cannot be reached, for example:
* Computing dynamical matrix for * * q = ( 0.0000000 0.1666667 0.0000000 )* * 2 Sym.Ops. (no q -> -q+G )* * G cutoff = 609.4453 ( 20928 G-vectors) FFT grid: ( 50, 50,400)* * number of k points= 144 gaussian smearing, width (Ry)= 0.0100* * iter # 15 total cpu time : 24287.3 secs av.it <http://av.it>.: 13.0* * thresh= 4.091E-07 alpha_mix = 0.700 |ddv_scf|^2 = 8.763E-11* *...* * iter # 59 total cpu time : 27386.7 secs av.it <http://av.it>.: 11.2* * thresh= 5.160E-05 alpha_mix = 0.700 |ddv_scf|^2 = 1.219E-06* *..* * iter # 100 total cpu time : 30214.5 secs av.it <http://av.it>.: 10.8* * thresh= 1.000E-02 alpha_mix = 0.700 |ddv_scf|^2 = 4.154E-02* * End of self-consistent calculation* * No convergence has been achieved* Due to the oscillating behavior of ddv_scf I doubt that increasing the iterations will in the end work. I tried increasing k points and cutoff well beyond SCF convergence (SCF shows convergence at 12x12x1 and ecutwfc~80 Ry but I went up to 36x36x1 and 120 Ry.) &inputph prefix = 'mgo', trans = .true. epsil = .false., fildyn = 'mgo.dyn', ldisp = .true. fildvscf = 'dvscf' amass(1) = 107.86820 amass(2) = 24.30500 amass(3) = 15.99990 outdir='./', nq1=6, nq2=6, nq3=1, tr2_ph = 1.0d-12, / The system is MgO stacked on top of Ag. The pseudos are NC from the ONCV library and work very well for the "pure" Ag and MgO separately. Any hint is very welcome! Best, Chris -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea
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