Thanks for the suggestion Stefano! Yet, lattice vector 3 is in my cell the largest and correspondingly nk3 must be larger than nk1=nk2, or? That's why I choose 10 10 6 (even if I might have to increase nk3 slightly).
Or do I miss something? I meanwhile also played with the cutoff of the wave functions (i.e. finding also an fft mesh which can be used with the symmetries which include a translation) but even if the fft mesh is 96x96x120 the symmetries which include the translation are neglected. I'll try with 96x96x128... Thomas On 08/09/2016 02:59 AM, stefano de gironcoli wrote: > I think that given your Bravais lattice nk3 must be equal to nk1 > so > 10 nk2 10 0 0 0 > or > 6 nk2 6 0 0 0 > should be fine > > 10 nk2 6 0 0 0 > is not > > the automatic unfolding of a grid generate additional points but this > does not mean they form a regular grid. think about what happens for an > hexagonal lattice with a shifted grid. > > stefano > > On 08/08/2016 17:51, Thomas Brumme wrote: >> Dear all, >> >> I want to calculate the phonon frequencies on a regular q mesh specified >> by using >> ldisp=.true. and the nq1, nq2, nq3 variables. Yet, I always get the error >> >> q-mesh breaks symmetry >> >> even if the grid has the same dimensions as the k mesh in the PWscf >> calculation. >> This is weird as the q mesh is exactly the same as the k mesh, which was >> created >> by applying the symmetries to a regular grid. The system is LCO and the >> input for >> PWscf (in the reduced cell) is: >> >> &control >> calculation = 'scf', >> restart_mode = 'from_scratch', >> prefix = 'LCO', >> pseudo_dir = './', >> outdir = './tmp/', >> nstep = 300, >> wf_collect = .true., >> / >> &system >> ibrav = 0, >> nat = 14, >> ntyp = 3, >> ecutwfc = 200, >> occupations = 'smearing', >> smearing = 'gauss', >> degauss = 0.01, >> nspin = 2, >> starting_magnetization(3) = 0.02, >> nr1 = 128, >> nr2 = 128, >> nr3 = 128, >> / >> &electrons >> electron_maxstep = 250, >> diagonalization = 'cg', >> conv_thr = 1.0d-10, >> / >> CELL_PARAMETERS (angstrom) >> 5.261112503 0.000000000 0.000000000 >> 0.000000000 5.330947322 0.000000000 >> -2.630556252 -0.000000000 6.548827231 >> ATOMIC_SPECIES >> La 138.90547 La1.UPF >> O 15.999 O.pz-n-mt.UPF >> Cu 63.546 Cu1.UPF >> K_POINTS automatic >> 10 10 6 0 0 0 >> ATOMIC_POSITIONS (crystal) >> ... >> >> I defined the FFT grid by hand since then the code does not drop the >> symmetries >> including fractional translations... Could this be the problem? Or that >> I did choose >> a FFT grid which has the same number of points in x/y/z directions? Or >> could this >> be due to a similar problem" as in hexagonal crystals where shifting the >> k mesh >> away from Gamma is a bad idea? Or is there an obvious error in my input >> for ph.x: >> >> &inputph >> tr2_ph = 1.0d-18, >> prefix = 'LCO', >> amass(1) = 138.90547, >> amass(2) = 15.999, >> amass(3) = 63.546, >> outdir = './tmp/', >> fildyn = 'LCO.dynG', >> ldisp=.true., >> nq1=10, nq2=10, nq3=6, >> fildvscf = 'LCO.dvscf', >> verbosity = 'high', >> / >> >> I searched the archive however I couldn't find a solution to my problem. >> Thus, any >> help would be very much appreciated :) >> >> Regards >> >> Thomas >> > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum -- Dr. rer. nat. Thomas Brumme Max Planck Institute for the Structure and Dynamics of Matter Luruper Chaussee 149 22761 Hamburg Tel: +49 (0)40 8998 6557 email: [email protected] _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
