[gmx-users] CO2 virtual site

[Sina Omrani]

Hi,
I have a problem when I use CO2 model with virtual sites during energy minimization. I used itp file in the md tutorial and beside the fact that some of my water molecules can not be settled, I get a positive potential energy and high force on molecules. Is something wrong?
And another question, Why virtual sites are introduced as atoms in itp file?
[ atomtypes ]
; name  bond_type    mass    charge   ptype          sigma      epsilon
  MCO   MCO          0.000   0.000    A              0.000      0.000
You can see that it is "A" as an atom not "D" or "V".