Really thanks for the reply. I didn't know that "Materials Studio" can do this. I tried Gaussian03, but it was crashed during the optimization.

The optimization was done by MS, but I want to demonstrate the charge density of molecule in a colorful pattern like this:

http://www.cosmologic.de/images/engineering/mol2.png

Actually, I want to estimate the activity coefficients of ionic liquids and the only software that I know are COSMOtherm or ADF COSMO-RS.

ADF has a trial version, but it only imports it's own file format plus ".cosmo" file.

I'm trying to test the output of Materials Studio in ADF COSMO-RS and see the result.

Dear Mehdi,

With ADF's COSMO-RS implementation you can also import sigma profiles generated with other programs. You can convert ASCII files to the binary format used by ADF's COSMO-RS module:

http://www.scm.com/Doc/Doc2013/COSMO-RS/page44.html

However, the parametrization is different for every COSMO-RS implementation, so it is recommended to generate the sigma profiles with ADF itself. This is easily done with the 'COSMO-RS compound' preset in the GUI which will set up the two necessary steps in one file: 1) optimization in the gas phase with the settings used for the parametrization, 2) single point COSMO calculation with infinite dielectric constant.

For an ionic liquid one would calculate the sigma profile of the cation and anion separately and make sure you would have a charge balance in the final COSMO-RS calculation. (I think people have also set up ionic liquids with COSMO-RS where the unit is a cation-anion pair).

Feel free to discuss these kind of questions with our support team or on the ADF mailing list.

Best wishes,

Fedor

Dear Fedor,

Thanks for your reply. It was very useful. I tried to optimize the cation and anion separately. Then imported them as two compounds in COSMO-RS module to calculate the activity coefficient.

I'm not sure how I should define the system. Should it be a 2-component system and mole fraction of cation and anion are defined as 0.5?

I did this procedure, but the result was from experimental value.

Thanks.

Mehdi

Dear Mehdi,

Perhaps you could send the outputs (or coskf files) to support to have a look at?

Best,

Fedor

Hi all,

I think my question is somehow related to the conversation going on here. Actually I am trying to create the cosmo file for H2S by Turbomole software. I am using B3LYP with whatever basis set that exist in the software but the result I get in the COSMOtherm in way off. Has any one had the experience of working with H2S? I appreciate it if any of you guys could help me.

Regards,

Hi Reza,

COSMO-RS has been parametrized with the BP86 functional and a prescribed basis set. So for consistency it is advisable to use the same set up.

Do you get reasonable results when you use the set procedure for generating the sigma profile?

-Fedor

Dear Mehdi,

Just to let you know that, with the help of Prof. Zhigang Lei's research group we now have a tutorial that explains how to use the 2-component procedure for ionic liquids with COSMO-RS (and also included an ionic liquid database).

http://www.scm.com/Doc/Doc2014/GUI/GUI_tutorial/page194.html

Dear Fedor,

Thanks for updating. It is what I was looking for, especially this statement:

the calculated activity coefficients have to be scaled with 0.5.

In the activity coefficient page, I think there is a typological error in the first equation.

γibin = (γibin xitern)/xibin

should be

γibin = (γitern xitern)/xibin

Regards,

Mehdi

Thanks, yes we should change that!

I wish to predict solubility of astaxanthin in mixtures of acetone and DMSO using UNIFAC software. How can i identify the functional groups of astaxanthin.

Structure of astaxanthin can be found in following link-- https://en.wikipedia.org/wiki/Astaxanthin