[gmx-users] On using CO2 as solvent

[Bao Kai]

Hi, all,

Following the tutorial on building biphasic system from Justin, I put the
decane in a box and equilibrated it first.  Then I increased the size of
the box.

Then I wanted to put some CO2 molecules to make a biphasic system.

When I used the following command to do that, I can only add 16 co2
molecules, which is really weird.
genbox_d -cp d10_newbox.gro -cs co2.gro -o d10_solv.gro -p d104.top

Resulting image can be found from the following link.
https://www.dropbox.com/s/slvqfrf4gftu9al/CO2_solvent.png

When I used
 genbox_d -cp d10_newbox.gro -cs  -o d10_solv.gro -p d104.top

More than 4000 water molecules were added.

Could you please tell me what happened here?

How to use co2 to be the solvent?

Thank you very much.

Best Regards,
Kai