[Pw_forum] Is geometry optimization same to MD?

nisihara225 at gmail.com nisihara225 at gmail.com
Sat Jun 13 06:47:07 CEST 2015

Dear Dr. Shaofeng Wang,

In solution, solvent molecules and ions do not take fixed structures by thermal motion.

Thus, geometry optimization is not suitable to discuss solvation structure.

And you will have to evaluate statistical average of solvent’s coordinates.

You can obtain the statistical average through DFT-MD calculation with some nano times.

However, DFT-MD takes too much computational costs.

On the other hand, 3D-RISM presents ‘directly’ the statistical average and requires little computational costs.

Also, it calculates solvation free energy simultaneously.

Now, you can use 3D-RISM to check out the repository of SVN:

  http://qeforge.qe-forge.org/svn/q-e/branches/espresso-3drismscf .

If you have any questions, please contact me.


Satomichi Nishihara (from Tokyo)

差出人: Shaofeng Wang
送信日時: ‎2015‎年‎6‎月‎13‎日 ‎土曜日 ‎11‎:‎49
宛先: pw_forum at pwscf.org

Dear all,

I have a question. I want to get the solvation structure of arsenic in 
solution. So, can I get a correct structure using relax instead of md? Do I 
need to make the system charge balance?

Thanks for any comments.


Shaofeng Wang, Ph.D
Environmental Molecular Science Group
Institute of Applied Ecology, Chinese Academy of Sciences
Shenyang, 110016, China
wangshaofeng at iae.ac.cn

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