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Prettyswan

木虫 (小有名气)

[交流] 【求助】结构优化中,如何选择POTIM? 已有6人参与

说明手册上说:
引用回帖:
Within all relaxation algorithms (IBRION=1,2 and 3) the parameter POTIM should be supplied in the INCAR file. For IBRION0, the forces are scaled internally before calling the minimization routine. Therefore for relaxations, POTIM has no physical meaning and serves only as a scaling factor. For many systems, the optimal POTIM is around 0.5. Because the Quasi-Newton algorithm and the damped algorithms are sensitive to the choice of this parameter, use IBRION=2, if you are not sure how large the optimal POTIM is.

这里推荐在结构优化中使用IBRION=2和POTIM=0.5.
在侯柱峰编写的《vasp软件包使用入门指南》中《§6.2结构参数的优化》中“一次成型”一节写道:
引用回帖:
SYSTEM = Mg-hex
ENCUT = 250
ISTART = 0; ICHARG = 2
ISMEAR = 1; SIGMA = 0.2
NSW = 60; IBRION = 2
ISIF = 3
POTIM = 0.2
EDIFF = 1E-6; EDIFFG = -1E-3
PREC = Accurate

那么应该如何选择POTIM的值呢?
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huangguiyang

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小木虫(金币+0.5):给个红包,谢谢回帖交流
zzy870720z(金币+2):谢谢指教,期待你更好的表现 2010-12-21 08:19:50
对于IBRION=2,POTIM不同值对效率影响不大的,就用0.5。如果对于初始结构严重偏离基态的,应先用较小的POTIM,例如0.1,0.05,甚至0.01。力减少到一定程度后,再用0.5.
4楼2010-12-21 06:03:56
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