Dear Gui,
in addition to the point mentioned by Lorenzo, I wonder if your c-axis
is large enough...
Let's say you calculate the Fe(110) surface by 3 layers, which is a good
starting point but
might be not enough, your system has a thickness of about 10 Angstrom -
2 times the
lattice spacing of Fe(110) plus the spacing iron-graphene plus the
graphene-oxygen distance.
This leaves 15 Angstrom or less for the distance between the repeated
slabs. This seems
rather small to me even if it might be enough. Additionally, you could
have a dipole in your
system due to charge transfer and thus you should add the dipole
correction. Especially,
the dipole could play an important role in the correct adsorption energy
and geometry
and thus also for the convergence of forces.
Regards
Thomas
On 3/6/19 10:02 AM, Gui Wei wrote:
Dear QE users,
I am trying to optimize the adsorption system that contain Fe(110)
substrate and single-layer graphene connected to an oxygen atom.I got
the total force and the energy like this.At first, everything was
fine,but after 0.006846 the total force began to increase ,causing the
total force not to converge ,it is a extremely strange result.Is there
any way to solve this problem?
Any suggestions would be greatly appreciated.
Thank you.
Total force = 0.316790 energy new = -4107.2627566975 Ry
Total force = 0.246608 energy new = -4107.3151393348 Ry
Total force = 0.156503 energy new = -4107.3635865834 Ry
Total force = 0.119628 energy new = -4107.3895957292 Ry
Total force = 0.078444 energy new = -4107.3969303863 Ry
Total force = 0.052366 energy new = -4107.4017754787 Ry
Total force = 0.040309 energy new = -4107.4042249914 Ry
Total force = 0.033754 energy new = -4107.4058726129 Ry
Total force = 0.028026 energy new = -4107.4071437156 Ry
Total force = 0.025319 energy new = -4107.4081667548 Ry
Total force = 0.024093 energy new = -4107.4089392392 Ry
Total force = 0.022277 energy new = -4107.4096467799 Ry
Total force = 0.019561 energy new = -4107.4102126980 Ry
Total force = 0.016523 energy new = -4107.4106348116 Ry
Total force = 0.014292 energy new = -4107.4109663982 Ry
Total force = 0.013121 energy new = -4107.4112149183 Ry
Total force = 0.011934 energy new = -4107.4114021825 Ry
Total force = 0.011261 energy new = -4107.4115692713 Ry
Total force = 0.010521 energy new = -4107.4117253881 Ry
Total force = 0.009179 energy new = -4107.4118535327 Ry
Total force = 0.008233 energy new = -4107.4119532022 Ry
Total force = 0.007949 energy new = -4107.4120378076 Ry
Total force = 0.007614 energy new = -4107.4121212783 Ry
Total force = 0.007100 energy new = -4107.4121953505 Ry
Total force = 0.006846 energy new = -4107.4122538477 Ry
Total force = 0.006967 energy new = -4107.4123143593 Ry
Total force = 0.007559 energy new = -4107.4123893617 Ry
Total force = 0.007912 energy new = -4107.4124672492 Ry
Total force = 0.007587 energy new = -4107.4125386594 Ry
Total force = 0.007532 energy new = -4107.4126143150 Ry
Total force = 0.008046 energy new = -4107.4126949028 Ry
Total force = 0.008145 energy new = -4107.4127766088 Ry
Total force = 0.008142 energy new = -4107.4128651944 Ry
Total force = 0.009356 energy new = -4107.4129774552 Ry
Total force = 0.011161 energy new = -4107.4131286975 Ry
Total force = 0.012473 energy new = -4107.4133389405 Ry
Total force = 0.013542 energy new = -4107.4136064842 Ry
Total force = 0.014769 energy new = -4107.4138982197 Ry
Total force = 0.015571 energy new = -4107.4142168735 Ry
Total force = 0.015344 energy new = -4107.4145642683 Ry
Total force = 0.015134 energy new = -4107.4149145704 Ry
Total force = 0.016511 energy new = -4107.4152819587 Ry
Total force = 0.016788 energy new = -4107.4156041418 Ry
&control
calculation = 'relax',
prefix='epoxy1',
restart_mode='from_scratch'
pseudo_dir = '/public/home/duan1/GuiWei/pseudo/',
outdir='/public/home/duan1/GuiWei/tempdir/'
tstress = .true.
tprnfor = .true.
etot_conv_thr=1.0D-4
forc_conv_thr=1.0D-3
/
&system
ibrav= 0,
nat=125,
ntyp=3,
nspin = 2
starting_magnetization(1) =0.4
occupations='smearing',
smearing='mp',
degauss=0.02,
ecutwfc =37.0
ecutrho =300.0
vdw_corr='DFT-D'
london_s6 = 0.75
/
&electrons
conv_thr = 1.0d-8
mixing_beta = 0.2
mixing_mode = 'local-TF'
mixing_ndim=16
electron_maxstep=200
/
&IONS
ion_dynamics='bfgs'
/
CELL_PARAMETERS angstrom
19.68000000000000 0.000000000000011 0.000000000000000
0.000000000000000 8.521689973238880 0.000000000000000
0.000000000000000 0.000000000000000 25.00000000000000
ATOMIC_SPECIES
Fe 55.847 Fe.pbe-nd-rrkjus.UPF
C 12.0107 C.pbe-rrkjus.UPF
O 16.00 O.pbe-rrkjus.UPF
ATOMIC_POSITIONS crystal
......
K_POINTS automatic
2 2 1 0 0 0
Wei gui
School of Mechanical Engineering，Chongqing University, China
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--
Dr. rer. nat. Thomas Brumme
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
Leipzig University
Phillipp-Rosenthal-Strasse 31
04103 Leipzig
Tel: +49 (0)341 97 36456
email: [email protected]
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