Dear All,<br><br><pre>I am trying to relax a surface slab of GaAs which has 72 atoms.<br>I found strange behaviour of first cycle of scf convergence.<br>The estimated scf convergence is huge. I terminated Ga surface using fractional charges<br>
H=1.25, which I downloaded from the quantum espresso official website.<br>When I use H=1, I don't see such a behaviour.<br>Can anyone kindly suggest the possible source of error on my part.</pre>First cycle of SCF convergence:<br>
<font size="1"> estimated scf accuracy < 3906.28215610 Ry<br> estimated scf accuracy < 39347.40892210 Ry<br> estimated scf accuracy < 18170.90673442 Ry<br> estimated scf accuracy < 15951.19730682 Ry<br>
estimated scf accuracy < 15662.52132268 Ry<br> estimated scf accuracy < 12286.77018220 Ry<br> estimated scf accuracy < 12233.77236956 Ry<br> estimated scf accuracy < 11694.83354422 Ry<br>
estimated scf accuracy < 15271.15048386 Ry<br> estimated scf accuracy < 15566.68838647 Ry<br> estimated scf accuracy < 47265.52643459 Ry<br> estimated scf accuracy < 22511.42062539 Ry<br>
estimated scf accuracy < 24008.31787289 Ry<br> estimated scf accuracy < 12935.76752149 Ry<br> estimated scf accuracy < 16811.33660587 Ry<br> estimated scf accuracy < 10992.92010369 Ry<br>
estimated scf accuracy < 4144.02105761 Ry<br> estimated scf accuracy < 30138.05735660 Ry<br> estimated scf accuracy < 10240.01360270 Ry<br> estimated scf accuracy < 16789.80502995 Ry<br>
estimated scf accuracy < 6254.96875173 Ry<br> estimated scf accuracy < 5678.83239125 Ry<br> estimated scf accuracy < 5653.94732457 Ry<br> estimated scf accuracy < 4634.85427954 Ry<br>
estimated scf accuracy < 4748.33851037 Ry<br> estimated scf accuracy < 4570.74005737 Ry<br> estimated scf accuracy < 2807.69984889 Ry<br> estimated scf accuracy < 5304.65877872 Ry<br>
estimated scf accuracy < 2066.38501462 Ry<br> estimated scf accuracy < 17495.61285271 Ry<br> estimated scf accuracy < 18676.38196709 Ry<br> estimated scf accuracy < 10884.14492461 Ry<br>
estimated scf accuracy < 17200.92388789 Ry<br> estimated scf accuracy < 1160.48758157 Ry<br> estimated scf accuracy < 1080.24247591 Ry<br> estimated scf accuracy < 399.14797137 Ry<br>
estimated scf accuracy < 122.19296219 Ry<br> estimated scf accuracy < 99.50315590 Ry<br> estimated scf accuracy < 55.04456371 Ry<br> estimated scf accuracy < 9.17378773 Ry<br>
estimated scf accuracy < 1.52941820 Ry<br> estimated scf accuracy < 4.24567233 Ry<br> estimated scf accuracy < 31.40572065 Ry<br> estimated scf accuracy < 0.15173499 Ry<br>
estimated scf accuracy < 0.25128323 Ry<br> estimated scf accuracy < 0.08254494 Ry<br> estimated scf accuracy < 0.04825066 Ry<br> estimated scf accuracy < 0.02330525 Ry<br>
estimated scf accuracy < 0.01482943 Ry<br> estimated scf accuracy < 0.00395579 Ry<br> estimated scf accuracy < 0.00021627 Ry<br> estimated scf accuracy < 0.00002718 Ry<br>
estimated scf accuracy < 0.00001596 Ry<br> estimated scf accuracy < 0.00000423 Ry<br> estimated scf accuracy < 0.00000096 Ry<br> estimated scf accuracy < 0.00000049 Ry<br>
estimated scf accuracy < 0.00000040 Ry<br> estimated scf accuracy < 0.00000004 Ry<br> estimated scf accuracy < 8.2E-09 Ry<br><br>My input file:<br><br> &CONTROL<br>
calculation = "relax" ,<br> restart_mode = 'from_scratch' ,<br> outdir='/tmp/GaAs/' ,<br> pseudo_dir = './' ,<br> prefix='GaAs'<br> disk_io = 'default' ,<br>
! verbosity = 'default' ,<br> tstress = .true. ,<br> tprnfor = .true. ,<br> nstep = 200 ,<br> etot_conv_thr = 1.0E-5 ,<br> forc_conv_thr = 1.0D-6 ,<br> ! iprint = 3 ,<br>
max_seconds = 6000000 ,<br> dt = 1000000 ,<br> /<br> &SYSTEM<br> ibrav = 0 ,<br> celldm(1) =7.383383939,<br> ! B = 3.70971016 ,<br> ! C = 3.70971016 ,<br> ! cosAB = 0.49517470 ,<br>
! cosAC = 0.49517470 ,<br> ! cosBC = 0.49517470 ,<br> nat = 72 , <br> ntyp = 3 , <br> ecutwfc = 40.0 ,<br> !ecutrho = 320.0 , <br>
occupations = 'smearing' ,<br> smearing = 'fd' ,<br> degauss = 0.005 ,<br> !nspin = 2 , <br> lda_plus_u = .false. , <br>
<br> !celldm(1) = 3.907118519,<br> !celldm(3) = 10.D0,<br><br> /<br> &ELECTRONS<br> electron_maxstep = 700 , <br> conv_thr = 1.0d-8 , <br> diagonalization = 'cg' , <br>
/<br> &IONS<br> bfgs_ndim =3,<br> pot_extrapolation='atomic',<br> /<br> &CELL<br> cell_dynamics = 'damp-w' ,<br> press = 0.00 ,<br> ! wmass = 0.00700000 ,<br> cell_dofree = 'xyz' ,<br>
/<br>CELL_PARAMETERS cubic <br> 2.00000 0.000000 0.000000<br> 0.00000 2.000000 0.000000<br> 0.00000 0.000000 10.00000<br>ATOMIC_SPECIES<br> Ga 69.723 Ga.rrkj3.UPF<br> As 74.922 As.rrkj3.UPF<br> H 1.00794 H-1.25.UPF<br>
ATOMIC_POSITIONS {alat} <br>Ga 0.00000050 -0.00000025 0.00682815<br>Ga 0.49999874 0.49924596 0.70857798<br>As 0.50000024 0.00000000 0.35277077<br>As -0.00000050 0.49920484 1.06302457<br>
Ga -0.00000075 1.00000049 0.00921110<br>Ga 0.50000024 1.50075426 0.70857948<br>As 0.49999949 1.00000074 0.35474173<br>As -0.00000050 1.50079488 1.06302507<br>Ga 0.00000000 0.00000050 1.42032605<br>
Ga 0.49999974 0.50287293 2.12975309<br>As 0.49999999 0.00000025 1.77702420<br>As 0.00000000 0.50483913 2.48497829<br>Ga -0.00000025 0.99999948 1.41672691<br>Ga 0.49999949 1.49712679 2.12975209<br>
As 0.49999974 0.99999923 1.77125600<br>As 0.00000000 1.49516135 2.48497904<br>Ga 0.00000025 -0.00000176 2.83068972<br>Ga 0.49999774 0.48620728 3.55158193<br>As 0.49999999 -0.00000125 3.18153191<br>
As -0.00000075 0.47707341 3.90604332<br>Ga -0.00000050 0.99999798 2.85092365<br>Ga 0.49999849 1.51379294 3.55158244<br>As 0.50000100 0.99999923 3.21014318<br>As 0.00000000 1.52292731 3.90604307<br>
Ga 0.00000000 0.00000025 4.30422216<br>Ga 0.49999974 0.55140319 4.97156294<br>As 0.49999974 0.00000075 4.67996164<br>As 0.00000000 0.69861686 5.30991586<br>Ga 0.00000000 0.99999948 4.21931590<br>
Ga 0.49999949 1.44859754 4.97156219<br>As 0.50000024 1.00000024 4.55459604<br>As 0.00000000 1.30138387 5.30991436<br>H 0.00000025 0.29006390 -0.24872539<br>H 0.00000000 -0.29006290 -0.24872389<br>
H -0.00000075 1.29045005 -0.24574939<br>H -0.00000075 0.70954892 -0.24574989<br>Ga 1.00000050 -0.00000025 0.00682815<br>Ga 1.49999874 0.49924596 0.70857798<br>As 1.50000024 0.00000000 0.35277077<br>
As 0.99999950 0.49920484 1.06302457<br>Ga 0.99999925 1.00000049 0.00921110<br>Ga 1.50000024 1.50075426 0.70857948<br>As 1.49999949 1.00000074 0.35474173<br>As 0.99999950 1.50079488 1.06302507<br>
Ga 1.00000000 0.00000050 1.42032605<br>Ga 1.49999974 0.50287293 2.12975309<br>As 1.49999999 0.00000025 1.77702420<br>As 1.00000000 0.50483913 2.48497829<br>Ga 0.99999975 0.99999948 1.41672691<br>
Ga 1.49999949 1.49712679 2.12975209<br>As 1.49999974 0.99999923 1.77125600<br>As 1.00000000 1.49516135 2.48497904<br>Ga 1.00000025 -0.00000176 2.83068972<br>Ga 1.49999774 0.48620728 3.55158193<br>
As 1.49999999 -0.00000125 3.18153191<br>As 0.99999925 0.47707341 3.90604332<br>Ga 0.99999950 0.99999798 2.85092365<br>Ga 1.49999849 1.51379294 3.55158244<br>As 1.50000100 0.99999923 3.21014318<br>
As 1.00000000 1.52292731 3.90604307<br>Ga 1.00000000 0.00000025 4.30422216<br>Ga 1.49999974 0.55140319 4.97156294<br>As 1.49999974 0.00000075 4.67996164<br>As 1.00000000 0.69861686 5.30991586<br>
Ga 1.00000000 0.99999948 4.21931590<br>Ga 1.49999949 1.44859754 4.97156219<br>As 1.50000024 1.00000024 4.55459604<br>As 1.00000000 1.30138387 5.30991436<br>H 1.00000025 0.29006390 -0.24872539<br>
H 1.00000000 -0.29006290 -0.24872389<br>H 0.99999925 1.29045005 -0.24574939<br>H 0.99999925 0.70954892 -0.24574989<br>K_POINTS automatic <br> 4 4 1 0 0 0</font><br><br>Best regards<br>
Magdalena Birowska<br><br>