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大司马

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[求助] foecite中的cvff力场问题

请问用foecite中的cvff力场优化是出现如下情况是什么原因,如何解决?


Energy Server failed.
The typing engine has failed to calculate a forcefield type for 2 particles.
Unable to calculate energy and gradients.
Geometry optimization finished with an error condition.



具体txt文档:
Forcite
-------
Task             : Geometry Optimization
Version          : 5.0
Build date       : Oct 22 2009
Host             : z-PC
Threads          : Scalar
Operating system : Windows
Task started     : Sun Mar 30 22:43:00 2014

---- Geometry optimization parameters ----

Algorithm                       : Smart
Convergence tolerance:
  Energy                        : 0.001 kcal/mol
  Force                         : 0.5 kcal/mol/A
Maximum number of iterations    : 500
External pressure               : 0 GPa
Motion groups rigid             : NO
Optimize cell                   : NO

---- Energy parameters ----

Forcefield                      : cvff
Electrostatic terms:
  Summation method              : Atom based
  Truncation method             : Cubic spline
  Cutoff distance               : 12.5 A
  Spline width                  : 1 A
  Buffer width                  : 0.5 A

van der Waals terms:
  Summation method              : Ewald
  Accuracy                      : 0.001 kcal/mol
  Repulsive cutoff              : 6 A
  Buffer width                  : 0.5 A

Energy Server failed.
The typing engine has failed to calculate a forcefield type for 2 particles.
Unable to calculate energy and gradients.
Geometry optimization finished with an error condition.




Task terminated               : Sun Mar 30 22:43:01 2014
Total CPU time used by Forcite: 1 seconds (1.23s)

Termination status : Error
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pigrass

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【答案】应助回帖

★ ★
月只蓝: 金币+2, 应助指数+1, 感谢指导! 2014-03-31 17:11:04
经常看到这样的问题,简单说就是“自动分配力场”不能识别结构中的部分原子
直接摘抄 help 的原文

If typing fails
Why typing may fail
Forcite needs the forcefield type of each atom in the structure in order to determine which forcefield parameters to use. In some cases, forcefield typing may fail. If this happens, you will not be able to run a Forcite calculation.

Common reasons for forcefield typing to fail

Structure is incorrect.

When assigning forcefield types, Materials Studio will look at the properties of the atom being typed and its microchemical environment. The properties and the extent of the microchemical environment examined varies with each forcefield and with each forcefield type; however, typically, the element type and hybridization of the atom, along with the bond type to neighboring atoms, will be considered.

Forcefield has not been parameterized for the structure or functional groups it contains.

An empirical forcefield is parameterized only for specific elements in selected structures and functional groups.

Tip: Select View | Project Log from the menu bar to check whether any error or warning messages have been reported.

If typing fails
Check that the structure is correct. For example, a structure that is aromatic (such as benzene) must either be in a Kekulé (alternate single and double bonds) or resonant (partial double bonds) representation. Similarly, a resonant structure must follow these rules. Thus, a nitro group must contain either a single and a double nitrogen-oxygen bond or both must be partial double bonds.
Check the forcefields Help topics to ensure that the forcefield is appropriate. There may be another forcefield that has been parameterized for this structure.
Note: Forcefield types and charges should only be assigned manually as a last resort. If this is done, any results obtained should be checked carefully.

Note: If you wish to preserve the forcefield types you assign, you should uncheck the Calculate automatically checkbox on the Forcite Preparation Options dialog.
#有问题发论坛,不接受私聊#爱晶体,爱MaterialsStudio#MS专辑点击右边#http://emuch.net/taotie/41673.html#物性数据#http://webbook.nist.gov/chemistry/#
2楼2014-03-31 10:42:16
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