Your structure is a prime example where "charge sloshing" appears. That is, "rms" in the following does not decrease monotonically, but increases and decreases in an oscillatory behavior. Often this is accompanied with a changing sign in "dE" that has a large magnitude:
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N E dE d eps ncg rms ort
DAV: 1 -0.674675263873E+04 -0.67468E+04 -0.18532E+05 1408 0.124E+04
DAV: 2 0.641970417853E+03 0.73887E+04 -0.51762E+04 1152 0.187E+03
DAV: 3 -0.375999241483E+03 -0.10180E+04 -0.93399E+03 1536 0.466E+02
DAV: 4 -0.595569632725E+03 -0.21957E+03 -0.21185E+03 1536 0.101E+02
DAV: 5 -0.504986267212E+03 0.90583E+02 -0.16216E+03 1280 0.579E+01
DAV: 6 -0.573948735957E+03 -0.68962E+02 -0.68124E+02 1536 0.166E+01
DAV: 7 -0.499762978097E+03 0.74186E+02 -0.99068E+02 896 0.377E+01
DAV: 8 -0.536179964928E+03 -0.36417E+02 -0.35934E+02 1536 0.449E+00 0.233E+02
DAV: 9 -0.154398344554E+05 -0.14904E+05 -0.14309E+05 1472 0.239E+03 0.135E+03
DAV: 10 -0.171134675562E+05 -0.16736E+04 -0.10238E+05 1536 0.525E+02 0.743E+02
DAV: 11 -0.322590198541E+03 0.16791E+05 -0.11741E+05 1536 0.208E+03 0.221E+02
DAV: 12 -0.114713536264E+04 -0.82455E+03 -0.22575E+04 1408 0.717E+02 0.169E+02
DAV: 13 -0.371352473535E+04 -0.25664E+04 -0.33844E+04 1152 0.544E+02 0.189E+02
DAV: 14 -0.178004987504E+04 0.19335E+04 -0.20182E+04 1344 0.784E+02 0.104E+02
DAV: 15 -0.761124519163E+03 0.10189E+04 -0.65715E+03 1152 0.288E+02 0.103E+02
DAV: 16 -0.560149987189E+04 -0.48404E+04 -0.14354E+03 1344 0.341E+02 0.125E+02
DAV: 17 -0.660411088100E+03 0.49411E+04 -0.68448E+03 896 0.297E+02 0.613E+01
DAV: 18 -0.216042093994E+04 -0.15000E+04 -0.17281E+04 1344 0.349E+02 0.659E+01
DAV: 19 -0.503925818302E+03 0.16565E+04 -0.46861E+03 960 0.150E+02 0.475E+01
DAV: 20 -0.185831050787E+04 -0.13544E+04 -0.13994E+04 1344 0.106E+02 0.488E+01
DAV: 21 -0.211392801739E+04 -0.25562E+03 -0.21904E+04 1088 0.186E+02 0.426E+01
DAV: 22 -0.405689476247E+04 -0.19430E+04 -0.39483E+04 1216 0.117E+02 0.866E+01
DAV: 23 -0.159872402555E+04 0.24582E+04 -0.68853E+03 1088 0.204E+02 0.367E+01
DAV: 24 -0.513758376284E+03 0.10850E+04 -0.34184E+03 1024 0.215E+02 0.299E+01
DAV: 25 -0.218844280648E+04 -0.16747E+04 -0.57863E+03 1280 0.208E+02 0.449E+01
DAV: 26 -0.394096173978E+03 0.17943E+04 -0.64560E+03 896 0.161E+02 0.249E+01
DAV: 27 -0.135970501039E+04 -0.96561E+03 -0.61444E+02 1408 0.221E+02 0.390E+01
DAV: 28 -0.399318289758E+03 0.96039E+03 -0.39731E+03 960 0.122E+02 0.203E+01
...
This happens often for magentic systems, slabs or a combination of them.
Changing the
density mixer setting often remedies this problem, unfortunately not (immediately) in your case.
There are a few other options you can set in INCAR to help VASP finding a solution, though.
First, check the POSCAR if the structure seems reasonable. For this purpose, I have shifted the compound that is supposed to be adsorbed on the Yb-surface.
The Yb-Ge distance of ~2 Ang. seemed too close at first sight. Specifically, I have replaced the last 27 coordinates in your box by the following starting guess:
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0.381535 0.502732 0.411664 T T T
0.6286 0.502058 0.575086 T T T
0.637622 0.261528 0.410269 T T T
0.622763 0.758758 0.413884 T T T
0.87885 0.517553 0.412488 T T T
0.37835 0.486563 0.737684 T T T
0.634437 0.245359 0.736289 T T T
0.619578 0.742588 0.739904 T T T
0.875665 0.501384 0.738509 T T T
0.379542 0.492613 0.615688 T T T
0.627408 0.496007 0.697083 T T T
0.629792 0.508109 0.45309 T T T
0.380343 0.496682 0.53366 T T T
0.635629 0.251409 0.614293 T T T
0.636431 0.255477 0.532265 T T T
0.62077 0.748639 0.617908 T T T
0.621571 0.752707 0.53588 T T T
0.876857 0.507434 0.616512 T T T
0.877658 0.511503 0.534485 T T T
0.49976 0.618618 0.657289 T T T
0.50719 0.370003 0.655482 T T T
0.508783 0.378088 0.492471 T T T
0.501353 0.626703 0.494279 T T T
0.755848 0.377414 0.655894 T T T
0.75744 0.385498 0.492884 T T T
0.748418 0.626028 0.657702 T T T
0.750011 0.634113 0.494691 T T T
However, the modifications to the POSCAR might not be necessary in the following.
The general guideline to tackle convergence issues is to make the problem simpler and ramp up the difficulty step by step.
This essentially means, finding a PBE solution for the non-magnetic problem first, i.e. reducing the parameters in the INCAR.
For this purpose, it is usually sufficient to study the convergence at the Gamma point.
Bear in mind to use vasp_std, in order to be able to increase the k-point mesh in a subsequent run.
Following INCAR settings converge to an error dE < 1E-5 after
NELM=500 steps.
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NELM = 500
ALGO = DAMPED ; TIME = 0.01 # strongly damped electronic minimizer
EDIFF = 1E-05
ISMEAR = 0
SIGMA = 0.05
ENCUT = 500
MAXMIX = 40 # helps sometimes to reach electronic convergence faster
LMAXMIX = 6 # set this if you have f-electrons in your system
LREAL = Auto # faster for large unit cells
IMIX = 0 # linear density mixer
AMIX = 0.2
BMIX = 0.0001
AMIX_MAG = 0.8
BMIX_MAG = 0.0001
Here is an excerpt of the corresponding OSZICAR:
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N E dE d eps ncg rms ort
DAV: 1 0.771919199043E+04 0.77192E+04 -0.14049E+05 384 0.123E+04
DAV: 2 0.395915183534E+04 -0.37600E+04 -0.33616E+04 384 0.182E+03
DAV: 3 0.163444013484E+04 -0.23247E+04 -0.21988E+04 384 0.480E+02
DAV: 4 0.609520693352E+03 -0.10249E+04 -0.98950E+03 384 0.298E+02
DAV: 5 0.153589071904E+03 -0.45593E+03 -0.44401E+03 384 0.187E+02
SDA: 6 0.111046393773E+04 0.95687E+03 -0.54546E+03 384 0.545E+05 0.000E+00
DMP: 7 0.643080833850E+03 -0.46738E+03 -0.58340E+03 384 0.251E+05 0.383E+05
DMP: 8 0.305845645317E+03 -0.33724E+03 -0.19735E+03 384 0.132E+05 0.755E+04
DMP: 9 0.365760816412E+03 0.59915E+02 -0.22794E+03 384 0.107E+06-0.973E+05
...
DMP: 393 -0.385824339861E+03 -0.10792E-04 -0.10124E-04 384 0.763E-04 0.108E-02
DMP: 394 -0.385824349986E+03 -0.10125E-04 -0.94960E-05 384 0.713E-04 0.101E-02
DMP: 395 -0.385824359483E+03 -0.94971E-05 -0.89054E-05 384 0.667E-04 0.949E-03
1 F= -.38582436E+03 E0= -.38577599E+03 d E =-.967378E-01
Using the corresponding output (WAVECAR), I considered the "magnetic" PBE problem with by adding following lines to INCAR:
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MAGMOM = 64*0.6 9*0.6 10*0.6 8*0.6 # ferromagentic solution is the default choice, you probably can avoid this line
ISPIN = 2
ICHARG = 1 # use CHGCAR as initial density, not WAVECAR
OSZICAR of the run is given in the following:
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N E dE d eps ncg rms ort
SDA: 1 -0.385824368401E+03 -0.38582E+03 -0.14784E-01 384 0.148E+01 0.000E+00
DMP: 2 -0.385839129843E+03 -0.14761E-01 -0.26090E-01 384 0.133E+01 0.147E+01
DMP: 3 -0.385865151565E+03 -0.26022E-01 -0.34484E-01 384 0.120E+01 0.259E+01
DMP: 4 -0.385899516596E+03 -0.34365E-01 -0.40378E-01 384 0.107E+01 0.342E+01
DMP: 5 -0.385939729285E+03 -0.40213E-01 -0.44253E-01 384 0.951E+00 0.400E+01
DMP: 6 -0.385983780473E+03 -0.44051E-01 -0.46529E-01 384 0.848E+00 0.438E+01
...
DMP: 103 -0.386818189427E+03 -0.13809E-04 -0.12667E-04 384 0.756E-04 0.137E-02
DMP: 104 -0.386818202039E+03 -0.12612E-04 -0.11567E-04 384 0.690E-04 0.125E-02
DMP: 105 -0.386818213556E+03 -0.11516E-04 -0.10561E-04 384 0.629E-04 0.114E-02
DMP: 106 -0.386818224070E+03 -0.10515E-04 -0.96400E-05 384 0.573E-04 0.104E-02
DMP: 107 -0.386818233668E+03 -0.95973E-05 -0.87973E-05 384 0.521E-04 0.954E-03
1 F= -.38681823E+03 E0= -.38676919E+03 d E =-.980935E-01 mag= 0.0000
Next I have added the Van der Waals parameter
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# VDW settings
LVDW = .TRUE.
IVDW = 12
LDIPOL = .TRUE
IDIPOL = 3
to obtain an energy of:
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...
DMP: 144 -0.387616147707E+03 -0.10487E-04 -0.95253E-05 384 0.444E-04 0.105E-02
DMP: 145 -0.387616157224E+03 -0.95167E-05 -0.86341E-05 384 0.395E-04 0.949E-03
1 F= -.40878865E+03 E0= -.40874032E+03 d E =-.966684E-01 mag= -0.0000
From here on, I recommend to run a few ionic steps with the gamma point version to obtain a reasonable structure. Also, if you want to switch to ALGO = FAST, you might need to decrease
EDIFF further down to ~1E-7, otherwise RMM could fail.
Only, in the final step I would increase the k-points to find the relaxed structure at the precision you are looking for.
N.B.: Because you study a system with f electrons, you might want to add a
U-parameter to Yb and Rh to improve the description of the system.