Water and gas phase environment
Just Got Here
10:31:50 PM PDT - Wed, Apr 9th 2014
Dear friends,
    i am a new bie to Nwchem and Qm. I went through the Manual of Nwchem but
I have few questions.

1. How to add water in calculation
2. How to do optimization all the calculations
    in water environment or gas phase.

I accept apology that it may be present in
manual but I not find the direct answer to it.

I will be thankful to the answer..

Forum Regular
4:27:29 PM PDT - Thu, Apr 10th 2014
Hi Prash,

I am not entirely sure what kind of calculation you are trying to do. You might be interested in either QM/MM calculations where the environment is typically represented using some classical model. Or you might be interested in solvation models where the environment is modeled with some dielectric medium. If you are interested in the latter then the COSMO model is probably what you want: http://nwchemgit.github.io/index.php/Release62:COSMO_Solvation_Model. In COSMO water is the default solvent and is represented by a specific value of the dielectric constant.

I hope this helps somewhat, otherwise please provide some more details on what exactly you are trying to do and I can provide better targeted answers.

Huub

Just Got Here
4:37:40 AM PDT - Sun, Apr 13th 2014
Dear Huub,
Thank you for reply.

I want to see the how the solvent affects on geomatry of energy
minimised of molecule,such as solvent water, methanol, gas phase,
acetonitrile..

That means I want my compounds minimised energy structure
in all this solvent and gas phase. Then I want to see the changes
in geomatry of energy minimied structures in all this solvent.
Along this it is also found that at some time the solvent may
enhance or decrease the Transition state energy of reactions.
That means I want to know the Transition state energy of
reaction in all this solvent ( water , acetonitrile, methanol,
Gas phase).

  So I wondered how to add this effect in calculation..
I read the manual but I not find the the appropriate
directive to add this effect...

Hope so u get my point. I will be thankfull for your help.

I am looking forward for answer.


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