CHARMM Development Project Forums User Discussion & Questions Parameter Set Discussion VdW paramter and charges for acetone andchloroform

Can you please let me known where I can get the Vdw and charges used in CHARMM for pure acetone and pure
chloroform.

Thanks,

Ganesh Kamath

For acetone, you can take the VDW parameters used for methyl groups
and for the carbonyl, see N-methylacetamide. The charges should be determined
in the standard fashion via HF/6-31G* interaction energies with water. See
my web page for details.

http://www.pharmacy.umaryland.edu/faculty/amackere/param/force_field_dev.htm

As for chloroform, there are no parameters available for chlorine. You're best bet would
be to use OPLS parameters. Note that the LJ sigma values have to be converted to
Rmin via multiplication by 2**(1/6).

I'd suggest running pure solvent simulations of both acetone and chloroform to see
that the models you create yield reasonable densities and heats of vaporization for
the pure solvents. Perhaps someone out there has done this already.

alex