【转载】来自：http://blog.chinaunix.net/uid-8776431-id-3071555.html

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) 

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。