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...
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 1.965735211236888
DAV: 14 -0.113419607056E+01 0.11315E+00 -0.41088E-03 255 0.256E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 1.96574
0.109E-01
...





I encountered this WARNING once and again.
To my surprise, this warning appears in some given structure (bond length or lattice constant), but not all the cases.
Take the linear atomic chain for example, the calculation of the structure in some given bond length would encounter it, but the others (in some other given bond lengths) haven't this problem. What is going wrong?

Thanks.

The stdout info is given in the following:
vasp.4.6.21 23Feb03 complex
POSCAR found : 1 types and 1 ions
LDA part: xc-table for Ceperly-Alder, Vosko type interpolation para-ferro
POSCAR, INCAR and KPOINTS ok, starting setup
FFT: planning ... 1
reading WAVECAR
entering main loop
N E dE d eps ncg rms rms(c)
DAV: 1 0.165490540147E+01 0.16549E+01 -0.53167E+02 215 0.183E+02
DAV: 2 -0.169126536222E+01 -0.33462E+01 -0.27573E+01 360 0.193E+01
DAV: 3 -0.174998907543E+01 -0.58724E-01 -0.58724E-01 240 0.385E+00
DAV: 4 -0.175057330410E+01 -0.58423E-03 -0.58423E-03 320 0.401E-01
DAV: 5 -0.175061183117E+01 -0.38527E-04 -0.38527E-04 395 0.534E-02 0.332E+00
DAV: 6 -0.145026006105E+01 0.30035E+00 -0.18538E-01 250 0.190E+00 0.193E+00
DAV: 7 -0.124923867913E+01 0.20102E+00 -0.56471E-01 275 0.298E+00 0.246E-01
DAV: 8 -0.124639718018E+01 0.28415E-02 -0.12525E-02 250 0.751E-01 0.225E-01
DAV: 9 -0.124402951771E+01 0.23677E-02 -0.10521E-02 245 0.362E-01 0.261E-01
DAV: 10 -0.125612478913E+01 -0.12095E-01 -0.43465E-02 255 0.776E-01 0.453E-01
DAV: 11 -0.124739451524E+01 0.87303E-02 -0.66144E-03 255 0.336E-01 0.326E-01
DAV: 12 -0.124374708772E+01 0.36474E-02 -0.32062E-03 305 0.214E-01 0.200E-01
DAV: 13 -0.124734722810E+01 -0.36001E-02 -0.11521E-02 275 0.382E-01 0.429E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 1.965735211236888
DAV: 14 -0.113419607056E+01 0.11315E+00 -0.41088E-03 255 0.256E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 1.96574
0.109E-01
DAV: 15 -0.124351468927E+01 -0.10932E+00 -0.44338E-04 285 0.103E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 1.96574 new 2.00000
0.122E-01
DAV: 16 -0.124517161205E+01 -0.16569E-02 -0.16856E-03 260 0.167E-01 0.219E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 1.985765427780409
DAV: 17 -0.119848614436E+01 0.46685E-01 -0.58614E-04 270 0.935E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 1.98577
0.916E-02
DAV: 18 -0.124377994528E+01 -0.45294E-01 -0.21443E-04 260 0.503E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 1.98577 new 2.00000
0.117E-01
DAV: 19 -0.124482664718E+01 -0.10467E-02 -0.33763E-04 265 0.713E-02 0.135E-01
DAV: 20 -0.124369300210E+01 0.11336E-02 -0.24487E-04 230 0.612E-02 0.125E-01
DAV: 21 -0.124468090321E+01 -0.98790E-03 -0.71488E-05 220 0.386E-02 0.952E-02
DAV: 22 -0.124377476827E+01 0.90613E-03 -0.11885E-04 210 0.448E-02 0.130E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 2.033902610099436
DAV: 23 -0.135369235005E+01 -0.10992E+00 -0.53499E-05 245 0.341E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 2.03390
0.135E-01
DAV: 24 -0.123933050636E+01 0.11436E+00 -0.70919E-04 305 0.898E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.03390 new 2.00000
0.893E-02
DAV: 25 -0.124394842834E+01 -0.46179E-02 -0.86325E-04 295 0.875E-02 0.143E-01
DAV: 26 -0.124379215865E+01 0.15627E-03 -0.39337E-05 265 0.325E-02 0.131E-01
DAV: 27 -0.124475878969E+01 -0.96663E-03 -0.15600E-04 285 0.464E-02 0.107E-01
DAV: 28 -0.124375222362E+01 0.10066E-02 -0.14066E-04 210 0.513E-02 0.129E-01
DAV: 29 -0.124478539847E+01 -0.10332E-02 -0.15190E-04 210 0.493E-02 0.112E-01
DAV: 30 -0.124369731175E+01 0.10881E-02 -0.11890E-04 220 0.481E-02 0.125E-01
DAV: 31 -0.124480714326E+01 -0.11098E-02 -0.12736E-04 210 0.463E-02 0.116E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 2.007872621902653
DAV: 32 -0.126953097076E+01 -0.24724E-01 -0.10900E-04 210 0.472E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 2.00787
0.125E-01
DAV: 33 -0.124387865178E+01 0.25652E-01 -0.22156E-04 225 0.519E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00787 new 2.00000
0.123E-01
DAV: 34 -0.124369008159E+01 0.18857E-03 -0.43202E-04 220 0.596E-02 0.126E-01
DAV: 35 -0.124475572526E+01 -0.10656E-02 -0.10275E-04 245 0.433E-02 0.105E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 1.957040655448409
DAV: 36 -0.110537071179E+01 0.13939E+00 -0.81749E-05 210 0.409E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 1.95704
0.109E-01
DAV: 37 -0.124362903456E+01 -0.13826E+00 -0.97116E-04 240 0.144E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 1.95704 new 2.00000
0.115E-01
DAV: 38 -0.124474107979E+01 -0.11120E-02 -0.80549E-04 235 0.123E-01 0.103E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 2.020801908082521
DAV: 39 -0.131134663759E+01 -0.66606E-01 -0.62113E-05 215 0.408E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 2.02080
0.128E-01
DAV: 40 -0.124192514379E+01 0.69421E-01 -0.62041E-04 250 0.784E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.02080 new 2.00000
0.131E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 1.957026633411735
DAV: 41 -0.110510569035E+01 0.13682E+00 -0.91810E-04 245 0.821E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 1.95703
0.109E-01
DAV: 42 -0.124367593489E+01 -0.13857E+00 -0.10783E-03 255 0.146E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 1.95703 new 2.00000
0.117E-01
DAV: 43 -0.124469678900E+01 -0.10209E-02 -0.80559E-04 235 0.122E-01 0.933E-02
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 1.965575707617216
DAV: 44 -0.113308237270E+01 0.11161E+00 -0.47839E-05 215 0.377E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 1.96558
0.995E-02
DAV: 45 -0.124370678888E+01 -0.11062E+00 -0.80312E-04 240 0.119E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 1.96558 new 2.00000
0.116E-01
DAV: 46 -0.124473253686E+01 -0.10257E-02 -0.60807E-04 235 0.103E-01 0.103E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 1.977049990426080
DAV: 47 -0.117033626880E+01 0.74396E-01 -0.45537E-05 215 0.367E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 1.97705
0.901E-02
DAV: 48 -0.124377148026E+01 -0.73435E-01 -0.52652E-04 250 0.837E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 1.97705 new 2.00000
0.117E-01
DAV: 49 -0.124475959099E+01 -0.98811E-03 -0.36778E-04 240 0.756E-02 0.109E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 2.029003562613544
DAV: 50 -0.133783337541E+01 -0.93074E-01 -0.48775E-05 215 0.360E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 2.02900
0.132E-01
DAV: 51 -0.124041915607E+01 0.97414E-01 -0.77001E-04 250 0.899E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.02900 new 2.00000
0.123E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 2.011954970086456
DAV: 52 -0.128276571927E+01 -0.42347E-01 -0.10321E-03 250 0.901E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 2.01195
0.125E-01
DAV: 53 -0.124319159723E+01 0.39574E-01 -0.25766E-04 225 0.546E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.01195 new 2.00000
0.110E-01
DAV: 54 -0.124369189804E+01 -0.50030E-03 -0.56699E-04 220 0.622E-02 0.126E-01
DAV: 55 -0.124466392121E+01 -0.97202E-03 -0.51287E-05 240 0.351E-02 0.863E-02
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 1.965586422534559
DAV: 56 -0.113308025119E+01 0.11158E+00 -0.25661E-05 215 0.298E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 1.96559
0.997E-02
DAV: 57 -0.124379833234E+01 -0.11072E+00 -0.80629E-04 245 0.117E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 1.96559 new 2.00000
0.120E-01
WARNING: DENTET: can't reach specified precision
Number of Electrons is NELECT = 1.984792434952098
DAV: 58 -0.119542403516E+01 0.48374E-01 -0.59855E-04 235 0.104E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 2.00000 new 1.98479
0.855E-02
DAV: 59 -0.124386064152E+01 -0.48437E-01 -0.33496E-04 245 0.589E-02BRMIX: very serious problems
the old and the new charge density differ
old charge density: 1.98479 new 2.00000
0.121E-01
DAV: 60 -0.124469584003E+01 -0.83520E-03 -0.19595E-04 245 0.522E-02
1 F= -.12446958E+01 E0= -.12446958E+01 d E =0.000000E+00
writing wavefunctions
--------------------------------------------

the reason for this error message (DENTET) is that the Fermi level
cannot be determined accurately enough by the tetrahedron method (i.e, the integrated DOS stays different from the number of valence electrons)
please try (one of) the following:
--choose a different BZ integration scheme (ISMEAR)
--if you want or have to keep the tetrahedron integration,
-- increase the number of k-points (mind that Gamma has to be included in the k-mesh)
-- increase NEDOS

Thanks for your kind help.
I have tried your ideas.
It is work by changing the ISMEAR. But it seems be of no effect when the number of k-points or the NEDOS is increased.
I do want to keep the tetrahedron integration. Is there any other means to solve this problem?

Thanks a million.

i have the same problem
i tried to increase NEDOS but it doesn'T work
and if want to use the same Smearing method and my KPOINT-Mesh

please check if you k-mesh is appropriate to give a tetrahedron decomposition of the BZ that completely covers the volume of the BZ.

I encountered the same problem, I'm using ifort (10.1.013) and latest vasp code. The problem, at least for me, turned out the be compiler optimization.
When -xO was set (FFLAGS), ifort optimizes the code to use SSEx (-xW makes the code use SSE2), which gave a lot of "LOOP WAS VECTORIZED" warnings during compilation and during the run would give "BRMIX: very serious problems" errors. Without -xW/-xO the code runs fine. For me -i8 had the same effect as -xO

Also note, I found in personal tests and it was confirmed by google that using SSE2/SSEx doesn't actually speed up the code. Since the program keeps swapping between SSE and non SSE portions, the code is actually a little bit slower, even though the SSE portion itself runs faster. Overhead for the lose.

Dear Admin,

as per your reply

the reason for this error message (DENTET) is that the Fermi level
cannot be determined accurately enough by the tetrahedron method (i.e, the integrated DOS stays different from the number of valence electrons)

as i am doing Binding energy (BE) calculations, i need to maintain same settings for individual components, this same problem occurred for one part of the components of total system. So, if my focus is only on Final energy, can i ignore this Warning? else if i change the ISMEAR for part of the system, can i get reliable and comparable setting, to do BE estimate?

Regards

If you encounter this message during the iteration, it will not change the final result. If it appears in the final iteration, you should perhaps use a different smearing method. Note that this error is more likely to appear if you use Monkhorst pack grids and can often be removed by using a Gamma centered grid. In Vasp.6.1, this behavior is fixed by fractional occupations or the tetrahedra.

Either way note that you should not use the tetrahedron method, if your system is metallic and you want to do relaxations.