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guodonglin

至尊木虫 (职业作家)

[求助] vasp优化难收敛,请大家给我看看

vasp优化难收敛,请大家给我看看。INCAR如下:
SYSTEM=LPO
ENCUT=500
ISTART=0
ICHARG=2
NELM=80
EDIFF=0.1E-03
NSW=80
EDIFFG=-0.01
IBRION=2
ISIF=3
#RWIGS=1.535 1.233 0.820 1.164
#LORBIT=11
NGX=105;NGY=108;NGZ=50
LREAL=.TRUE.
ISMEAR=-5
SIGMA=0.14
GGA=PE
ALGO=Normal
PREC=Accurate
现在已经运行到60多步了,还不收敛,急啊,请大家给我点建议,谢谢大家


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jghe

金虫 (著名写手)

【答案】应助回帖

感谢参与,应助指数 +1
WDD880227(金币+1): 感谢提示 2012-02-18 19:42:47
guodonglin(金币+4): 有帮助 2012-02-18 19:50:03
uuv2010: 回帖置顶 2012-02-18 21:11:10
Efficient relaxation from an unreasonable starting guess

If you want to do an efficient relaxation from a configuration that is not close to the minimum, set the following values in the INCAR file (for briefness the recommended setup is lacking, see Sec. 6.2.3):

NELMIN = 5           #  do a minimum of four electronic steps
EDIFF  = 1E-2        #  low accuracy
EDIFFG = -0.3        #  accuracy of ions not too high
NSW    = 10          #  10 ionic steps in ions
IBRION =  2          #  use CG algorithm

This way only low accuracy will be required in the first few steps, but since a minimum of 5 electronic steps is done the accuracy of the calculated electronic groundstate will gradually improve. If you are a slightly advanced user you can also use the damped MD algorithm, which is usually more efficient than the CG one:

IBRION =  1 ; SMASS = 0.4  # damped MD  
POTIM  = 0.4         # time step needs to chosen with care

In this case, a too large POTIM will result in divergence.
5楼2012-02-18 19:18:42
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enola

捐助贵宾 (正式写手)

uuv2010(金币+1): 多谢提示 2012-02-18 21:11:00
还好吧,要是初始结构比较差,像我的话有时100多步才能完成。。
timeflies..
2楼2012-02-18 18:04:37
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enola

捐助贵宾 (正式写手)

WDD880227(金币+1): 感谢提示 2012-02-18 19:42:32
uuv2010(金币+1): 多谢提示 2012-02-18 21:11:06
而且你设置PREC=Accurate
timeflies..
3楼2012-02-18 18:04:59
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guodonglin

至尊木虫 (职业作家)

引用回帖:
: Originally posted by enola at 2012-02-18 18:04:37:
还好吧,要是初始结构比较差,像我的话有时100多步才能完成。。

我们可以通过什么方式,加快收敛速度,谢谢
4楼2012-02-18 19:01:41
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