AMBER Archive (2005)

Subject: Re: AMBER: D-enantiomers

From: Piotr Cieplak (cieplak_at_cgl.ucsf.edu)
Date: Thu Sep 22 2005 - 12:41:24 CDT


>> Point taken. It still seems a bit odd that the charges should change.

>Odd, but true ;-)
>Two dia. could have different global minima/conformatiom -> different charges

>> The connectivity is more or less the same (albeit different stereochem).
>
>The connectivity is related to the topology, and the connectivities 'can'
>obviously be the same in enantio./dia. But it is not because the connectivities
>are the same that the charges have to be the same...

This would go beyond the general philosophy of molecular mechanics,
where the whole system is build from simple basic units.
Going along Francois's line we would need totally different set of charges
for let's say GLY-ALA and ALA-GLY (all L-type).
I think the simplest case to show that the charges need to be the same in
R or S isomer would be to calculate them for le'ts say to optical
isomers of CHFCLBR

Piotr

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