Dear Matthew,
> True, but for the development of GLYCAM06 only HF/6-31G* and HF/6-31++G**
> were employed for optimizations.
ok - we will modify R.E.D. Server accordingly. thanks.
> Using MP2 for optimization would be very
> expensive for little gain. For parameter fitting, single point energies
> were calculated with B3LYP/6-31G* & B3LYP/6-31++G** depending on the
> molecule. The DFT method was found to give reasonable agreement for little
> cost when applied to sugars. Using higher levels of theory may get better
> gas phase results but when it comes to agreeing with solution rotamer
> populations, DFT is more cost effective and gives reasonable agreement. If
> someone knows of a QM/DFT study that shows a better way then we'll certainly
> explore that.
>
> It actually does make a difference in the cases of anionic systems. We've
> compared sulfate charges developed with HF/6-31G* and HF/6-31++G** and found
> that free energies of binding agree better with the 6-31++G** basis set.
ok for all ;-)
regards, Francois
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Received on Fri Sep 23 2011 - 03:00:03 PDT
