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ddwy

木虫 (小有名气)

[求助] 分子动力学模拟出错 已有1人参与

大家好:
我用DL_POLY做分子动力学模拟,CONTROL输入文件是:

temperature 298.15
# pressure 0.001
ensemble nvt hoover  0.5

integrat velocity
restart
steps 3000000
equilibration 1000000
mult  1
scale  5
stats 20
rdf            10
print rdf

traj 1000001 100 0

densvar 20

timestep 0.002
cutoff        12.0

ewald precision 1.0E-6

minimise energy 50 5.0E-03

shake 1.0E-6
mxshak  10000
quaternion tolerance  1.0E-05

job time       99999999999999.0
close time     200000.0

finish
但是计算到第步的时候出现错误,OUTPUT文件为:
----------------------------------------------------------------------------------------------------------------------------------
   174600 -2.8822E+04  2.9815E+02 -3.1606E+04  3.9295E+03 -3.5876E+04  1.7169E+02  1.0398E+02  6.5269E+01  0.0000E+00
349.20000 -2.9405E+04  0.0000E+00  9.0503E+03 -9.0711E+04  3.5875E+04  8.3469E+01  0.0000E+00  6.3803E+04  0.0000E+00
119751.3  4.9579E+04  0.0000E+00  0.0000E+00  0.0000E+00  9.0000E+01  9.0000E+01  9.0000E+01  0.0000E+00 -1.2860E+00

  rolling -2.6814E+04  2.9487E+02 -2.9563E+04  4.1468E+03 -3.4341E+04  3.6908E+02  1.8861E+02  7.4187E+01  0.0000E+00
averages -2.6525E+04  0.0000E+00  6.3658E+03 -9.3434E+04  3.4340E+04  1.4041E+03  0.0000E+00  6.4056E+04  0.0000E+00
           4.9579E+04  0.0000E+00  0.0000E+00  0.0000E+00  9.0000E+01  9.0000E+01  9.0000E+01  0.0000E+00 -8.0166E-02
----------------------------------------------------------------------------------------------------------------------------------

*** warning - global constraint number         6 , with particle numbers:      2885 &      2886 ,
converges to a length of     7.94 Angstroms with a factor  3.1039E+01 ,contributes towards next error !!! ***

*** warning - global constraint number         7 , with particle numbers:      2885 &      2887 ,
converges to a length of    12.88 Angstroms with a factor  8.2412E+01 ,contributes towards next error !!! ***

*** warning - global constraint number         8 , with particle numbers:      2886 &      2887 ,
converges to a length of    18.15 Angstroms with a factor  1.0006E+02 ,contributes towards next error !!! ***

DL_POLY_4 terminated due to error   105

error - shake algorithm (constraints_shake) failed to converge
"OUTPUT" 64939L, 6075639C                     


请各位指点一下,谢谢
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我喜欢收集微笑没有原因……
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lsloneil

专家顾问 (正式写手)

【答案】应助回帖

感谢参与,应助指数 +1
http://www.uark.edu/ua/fengwang/DLPOLY2/node350.html

Message 105: error - shake algorithm failed to converge

The RD-SHAKE algorithm for bond constraints is iterative. If the maximum number of permitted iterations is exceeded, the program terminates. Possible causes include: a bad starting configuration; too large a time step used; incorrect force field specification; too high a temperature; inconsistent constraints involving shared atoms etc.
Action:
Corrective action depends on the cause. It is unlikely that simply increasing the iteration number will cure the problem, but you can try: follow the standard user response to increase the control parameter mxshak. But the trouble is much more likely to be cured by careful consideration of the physical system being simulated. For example, is the system stressed in some way? Too far from equilibrium?

试试从以上提出的可能性来查找错误。另外,怎么没看见shake tolerance关键字?
2楼2014-09-04 10:45:22
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ddwy

木虫 (小有名气)

引用回帖:
2楼: Originally posted by lsloneil at 2014-09-04 10:45:22
http://www.uark.edu/ua/fengwang/DLPOLY2/node350.html

Message 105: error - shake algorithm failed to converge

The RD-SHAKE algorithm for bond constraints is iterative. If the maximum number of p ...

shake 1.0E-6
mxshak  10000
上面这一部分信息不是shake tolerance的设置吗?
我喜欢收集微笑没有原因……
3楼2014-09-05 16:13:18
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