Quoting Mike Wykes <wykesm.averell.umh.ac.be>:
> I guess I'd have to try scaling the charges, then check the agreement of
> the liquid properties with experimental results, then change the VDWs
> params and check again, and then try combinations of changes in charges
> & VDWs and check the properties again. This seems like a huge job though.
In R.E.DD.B., for a solvent several sets of charge values are
available; i.e. not only the W-46 project... See:
W-49 Organic solvent
W-48 Organic solvent
W-47 Organic solvent
W-46 Organic solvent
W-40 Benzene
W-35 Acetonitrile
The sets of charge values are different !
You could also easily derive your own sets of charge values using R.E.D.:
For instance:
-1- RESP charges with Connolly surface for the MEP.
HF/6-31G* Connolly surface algo., 2 stage RESP fit qwt=.0005/.001
=> Different sets of molecular orientations can be used to generate
slightly different sets of charge values (in your case a single
conformation is possible for benzene & acetonitrile).
-2- ESP charges with Connolly surface for the MEP.
HF/6-31G* Connolly surface algo., 1 stage RESP fit qwt=.0000
=> Different sets of molecular orientations can be used to generate
slightly different sets of charge values.
-3- RESP charges with CHELPG for the MEP ("GLYCAM").
HF/6-31G* CHELPG algo., 1 stage RESP fit qwt=.01
=> Different set of molecular orientations can be used to generate
slightly different sets of charge values.
-4- ESP charges with CHELPG for the MEP.
HF/6-31G* CHELPG algo., 1 stage RESP fit qwt=.00
=> Different set of molecular orientations can be used to generate
slightly different sets of charge values.
This make 4 R.E.D. runs & in each run you can even generate several
sets of charge values depending on the molecular orientations
selected. For instance, by providing three .p2n files & a single .log
GAMESS/Gaussian output (& three symbolic links):
GAMESS-Gaussian-QM-output.log: three symbolic links
Mol_red1.log
Mol_red2.log
Mol_red3.log
Mol_red1.p2n
without the "REMARK REORIENT ..." keyword: to keep the molecular
orientation of the QM program
Mol_red2.p2n
Add the "REMARK REORIENT X Y Z" keyword: a single reorientation is selected
Mol_red3.p2n
Add the "REMARK REORIENT X Y Z| Z Y X" keyword: two reorientations are
selected
See
http://q4md-forcefieldtools.org/Tutorial/Tutorial-1.php#3 for more
information and in particular "General information about molecular
orientation and charge values"
Thus, in 5 minutes you generate 3 x 4 = 12 sets of charge values for a
solvent... Then, if you can show than one charge model is "better"
than another one it is nice.
regards, Francois
-----------------------------------------------------------------------
The AMBER Mail Reflector
To post, send mail to amber.scripps.edu
To unsubscribe, send "unsubscribe amber" to majordomo.scripps.edu
Received on Sun Feb 17 2008 - 06:07:44 PST
