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lijuanshu

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[交流] 静态计算时出现警告

静态计算时的INCAR如下：
SYSTEM =
ENCUT =
ISTART = 0
ICHARG = 2
ISMEAR = -5
ISPIN = 2
NELM = 2000
EDIFF = 1E-4
IALGO = 48
LREAL = Auto
GGA = 91
VOSKOWN = 1
但是在计算中出现警告如下：
RMM:  22 -0.310967594429E+03 0.21293E+00 -0.24248E+00 10244 0.439E+00 0.422E+01
  WARNING: DENTET: can't reach specified precision
  Number of Electrons is NELECT = 476.996768664236
RMM:  23 -0.310376643978E+03 0.59095E+00 -0.83636E-01 10268 0.266E+00 0.375E+01

RMM:  43 -0.309736141363E+03 0.53076E-02 -0.50929E-02 10165 0.574E-01 0.356E+00
RMM:  44 -0.309811626871E+03 -0.75486E-01 -0.48571E-02 10210 0.597E-01 0.369E+00
  WARNING: DENTET: can't reach specified precision
  Number of Electrons is NELECT = 477.041023713897
RMM:  45 -0.309698348515E+03 0.11328E+00 -0.13902E-02 10260 0.310E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 476.99930 new  477.04032
0.319E+00
  WARNING: DENTET: can't reach specified precision
  Number of Electrons is NELECT = 476.985853390457
RMM:  46 -0.310016610388E+03 -0.31826E+00 -0.42439E-02 10215 0.447E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 477.04032 new  476.98515
0.296E+00
RMM:  47 -0.309997772396E+03 0.18838E-01 -0.27267E-02 10259 0.413E-01BRMIX: very serious problems
the old and the new charge density differ
old charge density: 476.98515 new  476.99930
0.198E+00
RMM:  48 -0.310064999937E+03 -0.67228E-01 -0.44514E-02 10200 0.397E-01 0.171E+00
这些警告对电荷密度的结果有影响吗？应该如何消除？

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1楼2013-03-05 16:19:38

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hypnos

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lijuanshu(金币+1): 谢谢参与

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

以上是vasp论坛对此类问题的回复

大意是费米能级不能精确确定。解决办法有如下三条：
1. 改变ISMEAR（如使用ISMEAR=0）
2. 增加K点
3. 增加NEDOS（DOS的采点个数）