vasp运行中常见错误的解决 (2010-02-03 02:15)
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标签： - 分类： Vasp
有时，VASP在电子自洽计算的中间步骤中会出现如下的错误 WARNING: DENTET: can't reach specified precision Number of Electrons is NELECT = 196.0137087990377
RMM: 7 -0.461353114525E+03 0.15540E+03 -0.29356E+02 6562 0.456E+01BRMI X: very serious problems
the old and the new charge density differ old charge density: 195.99999 new 196.01370 0.758E+01
RMM: 8 -0.228026134405E+03 0.23333E+03 -0.10404E+02 4963 0.286E+01BRMI X: very serious problems
the old and the new charge density differ old charge density: 196.01370 new 195.99999 0.376E+01
出现此警告(DENTET)的原因是因为无法通过tetrahedron方法得到足够精确的费米能级。也就是将态密度积分到费米面的电子数和体系的价电子数目不一致。可以尝试采用以下方法得以解决此问题：
a)选择另一种布里渊区内的积分方法(改变ISMEAR)
VASP计算中Sub-Space-Matrix is not hermitian in DAV的错误 我在计算界面体系时候，其他计算条件不变，仅改变了一些k格点数，就一直提示如下的错误：
DAV: 13 -0.242323773333E+03 0.98155E+02 -0.87140E+01 48832 0.949E+01BRMIX: very serious problems the old and the new charge density differ old charge density: 252.00012 new 252.29979 0.809E+01
DAV: 14 -0.392866843695E+03 -0.15054E+03 -0.76122E+01 50857 0.731E+01BRMIX: very serious problems the old and the new charge density differ old charge density: 252.29979 new 252.48257 0.484E+01
WARNING: Sub-Space-Matrix is not hermitian in DAV 9 0.133520549894753
WARNING: Sub-Space-Matrix is not hermitian in DAV 17 495.153990161108
WARNING: Sub-Space-Matrix is not hermitian in DAV 6 0.250235927490523
WARNING: Sub-Space-Matrix is not hermitian in DAV 9 1876.75162244581
解决办法只需调整 AMIX, BMIX的值，把他们设置小一些。
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Moderators: admin.
Author Post
TING QIN
Tue May 23 2006, 02:59PM
Registered Member #523 Joined Tue Jan 10 2006, 12:13PM posts 4
Hi, I do calculations for transition metals with respect to primitive monoclinic structure containing 16 atoms. VASP runs in the cluster and uses 4 processors. The INCAR is listed below: SYSTEM = A12 ENCUT = 330 EDIFF=0.000001 ISMEAR =1 SIGMA = 0.1 IBRION=2 ISIF=3 NSW=1000 EDIFFG = -0.01 AMIX = 0.02
During the electronic structure relaxation, it always display lots of warning messages “WARNING: Sub-Space-Matrix is not hermitian in DAV 4” and eventually the calculation fails with such error message “Error EDDDAV: Call to ZHEGV failed. Returncode = 47 315”
As seen, I set AMIX from the default value of 0.4 to 0.02, and the problem still exists.
What is the reason and how can I avoid such problem? Many thanks.
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admin
Tue May 23 2006, 03:45PM
posts 1693
there may be several reasons for this error, the most common are 1a) the input geometry was not reasonable (error occurs at the very first ionic step) or
1b) the last ionic relaxation step lead to an unreasonable geometry (compare the input and output geometries of the
last ionic relaxation steps). In that case it can be helpful to --> switch to a different relaxation algorithm (IBRION-tag) --> reduce the step size of the first step by setting POTIM explicitely 2) If this error shows up at all your calculations: The installation of the LAPACK on your machine was not done properly: use a different LAPACK, e.g. the LAPACK which is delivered with the code (vasp.4.lib/lapack_double.o)
3) on some architectures (especially SGI) some Lapack routines are not working properly. However, it is possible to avoid the usage of the ZHEGV subroutine by commenting the line #define USE_ZHEEVX in
davidson.F, subrot.F, and wavpre_noio.F and recompiling VASP.
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sridevi
Tue May 30 2006, 04:47PM
Registered Member #544
Joined: Tue Jan 24 2006, 04:13PM posts 5
I got the same problem.
If you are using vasp 4.6. Try using \ It solved the problem for me.
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jcconesa
Sun Jan 07 2007, 07:06PM
Registered Member #760
Joined: Mon Jul 03 2006, 12:48PM Location: Madrid posts 10 Hi,
I got the same problem on a sgi machine when running the Cu benchmark. Changing to IALGO=48 just changed the problem; then I get the messages: .............
lib-4201: UNRECOVERABLE library error.
Encountered during a direct access unformatted READ from unit 21. Fortran unit 21 is connected to a direct unformatted unblocked file: \ IOT trap
core dumped .....................
These messages appeared after 20 cycles of RMM: and one line beginnig with
1 T= 2080. E= -.90209009E+04 E0=...
Please help to solve. Concerning previous admin comments I should say that in the davidson, subrot and wavpre_noio files the variable \