Hello, A few issues I could spot by looking at the input. Should use only 1 k point along the direction of the vacuum. Also, it will be more reasonable if the number of k points in the direction of celldm(2) is about twice of that in the direction of celldm(1). The ecutwfc is too large, 60-80 Ry should be fine.
Best wishes, Biswajit Biswajit Santra Mobile: +1-609-227-9202 http://www.princeton.edu/~bsantra/ On Mon, Feb 20, 2017 at 12:13 PM, Namita Narendra <[email protected]> wrote: > Hi, > > I am trying to relax a (111) diamond/cubic-BN slab and the total force on > the atom is not converging. Initially, the scf cycle itself was not > converging and I needed to introduce smearing with degauss=0.01 to achieve > scf convergence. Now, the relaxation is not converging and the total force > on the atom is oscillating. I have tried mixing of 'local-TF', reduced > mixing_beta, used damped ion dynamics and tried LDA pseudopotential. None > of this has helped with the convergence issue. Attached below is the input > file used. > > &CONTROL > calculation = 'relax' , > restart_mode = 'from_scratch' , > wf_collect = .true. , > outdir = '/share2/nnarend/espresso/c_bn1' , > pseudo_dir = '/home/nnarend/pseudo' , > prefix = 'C_BN_1' , > tstress = .true. , > tprnfor = .true. , > forc_conv_thr=1.0D-3, > etot_conv_thr=1.0D-4 > / > &SYSTEM > ibrav = 8, > celldm(1) = 8.291523, > celldm(2)=0.57735, > celldm(3)=6, > nat = 24, > ntyp = 3, > ecutwfc=180.0, > occupations='smearing', > smearing='cold', > degauss=0.01 > > / > &ELECTRONS > conv_thr = 1.0d-8, > mixing_mode = 'plain' , > mixing_beta = 0.3 , > diagonalization = 'david' , > / > &IONS > / > ATOMIC_SPECIES > B 10.811 B.pbe-nc.UPF > N 14.007 N.pbe-nc.UPF > C 12.011 C.pbe-nc.UPF > > ATOMIC_POSITIONS alat > C 0.000000 0.000000 0.000000 > C 0.500000 0.288675 0.000000 > C 0.166667 0.288675 0.117851 > C 0.666667 0.000000 0.117851 > C 0.166667 0.288675 0.471404 > C 0.666667 0.000000 0.471404 > C 0.333333 0.000000 0.589255 > C 0.833333 0.288675 0.589255 > C 0.333333 0.000000 0.942808 > C 0.833333 0.288675 0.942808 > C 0.000000 0.000000 1.060659 > C 0.500000 0.288675 1.060659 > B 0.000000 0.000000 1.414212 > B 0.500000 0.288675 1.414212 > N 0.166667 0.288675 1.532063 > N 0.666667 0.000000 1.532063 > B 0.166667 0.288675 1.885616 > B 0.666667 0.000000 1.885616 > N 0.333333 0.000000 2.003467 > N 0.833333 0.288675 2.003467 > B 0.333333 0.000000 2.357020 > B 0.833333 0.288675 2.357020 > N 0.000000 0.000000 2.474871 > N 0.500000 0.288675 2.474871 > > K_POINTS automatic > 8 8 6 0 0 0 > > Below is the force at the end of each bfgs cycle > > Total force = 0.492043 Total SCF correction = 0.000193 > Total force = 0.170844 Total SCF correction = 0.000253 > Total force = 0.049967 Total SCF correction = 0.000085 > Total force = 0.038773 Total SCF correction = 0.000075 > Total force = 0.042155 Total SCF correction = 0.000056 > Total force = 0.046807 Total SCF correction = 0.000072 > Total force = 0.044401 Total SCF correction = 0.000064 > Total force = 0.034652 Total SCF correction = 0.000095 > Total force = 0.033861 Total SCF correction = 0.000065 > Total force = 0.107334 Total SCF correction = 0.000129 > Total force = 0.071144 Total SCF correction = 0.000057 > Total force = 0.053109 Total SCF correction = 0.000077 > Total force = 0.058897 Total SCF correction = 0.000087 > Total force = 0.075144 Total SCF correction = 0.000061 > Total force = 0.109071 Total SCF correction = 0.000025 > Total force = 0.121561 Total SCF correction = 0.000042 > Total force = 0.128205 Total SCF correction = 0.000048 > Total force = 0.138713 Total SCF correction = 0.000070 > > Thanks, > Namita > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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