AMBER Archive (2006)

Subject: Re: AMBER: ab initio terminology query

From: David A. Case (
Date: Wed Nov 01 2006 - 11:30:50 CST

On Wed, Nov 01, 2006, Ross Walker wrote:
> > > In the following example: Data was computed at the
> > > "B3LYP/6-31++G(2d,2p)//HF/6-31G(d) level of theory"
> In the case of the FF94, 96, 99XX force fields the level of theory used for
> the single point calculations was HF/6-31G(d). The reason for this is that
> this combination fortuitously underestimates the charges in gas phase giving
                               should be "overestimates the bond dipoles"

> If you use a higher level of theory for the ESP calculation you will
> over polarise your molecule when simulating it in solvent.
   should be "under-polarize" [This is an American-English list :-)) ]

Only the original author can really say what was meant by the phrase
quoted at the very top. My original read was the same as that of Ross,
although it seems like unusually large basis set in which to do optimization.
But Jiri is also correct in pointing out that this *is* a standard qchem
notation; that interpretation, however, would imply the use of a very
non-standard set of RESP charges. Absent definitive information, we're all
just guessing.


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