Subject: CCL: AMSOL Charges from AM1 SM2

From: Mr Andrew D Allen <[email-masked]>
Date: Wed, 9 Nov 94 9:56:15 GMT

Dear Netters,

I have observed an increase of dipole, due to increases in the magnitude
of the charge on atoms, in uridine 2'monophosphate. The details of my
calculations are as follows:-

Gas phase structure fully optimised using AM1 and POWELL method, to a gradient
of 0.04 kcal/Ang. Aqueous phase structure is using the frozen gas phase
geometry and AM1 SM2 with 1SCF.

Relevant output:-

                         Gas Phase      Aqueous Phase
Dipole moment  (Debye)    12.80612        17.61578 
Charges on PO3H
                   P       2.5377          2.7478
                   O      -1.1339         -1.2895
                   O      -1.1467         -1.2316
                   O      -0.8227         -0.8255
                   H       0.2381          0.2514

	I was always lead to believe that an polar solvent stabilised
the high charges on functional groups such as phosphates. Such that 
the magnitude of the charges was reduced, this would in theory reduce
the dipole moment. Here however the magnitude of the charges has increased!

Can anyone (Chris!) explain this?

Andy

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