Dear Xueqin Pang,
> I intend to get the partial charges of DPPC (C40H80NO8P) with RESP
> after optimization with Gauss. However the output of Gauss for the
> lipid (dppc) differs a lot from the input conformation.
What is this input conformation ? Where does it come from ?
> What is more, after stimulating with AM1-BCC and RESP, the
> given partial charges of the gout is quite different, espancially
> for the N atom, which is .-0.58700 in AM1-BCC, but 0.060945 from RESP.
Difficult to answer here.
Are you sure the way for deriving the RESP charges for your molecule
is correct ? Did you use R.E.D. ? You need a P2N input file: I can
help you to prepare it if you have problems for that.
> So do you have any suggestions on what to do with Gauss. and which
> partial change should I use?
From what I quickly saw your input is huge... Based on which criteria
did you select the conformation used in MEP computation ? Based on
luck ?
Then, the charges of the Hs of a methyl group as well as those of the
methylene have to be equivalenced. The charges of the ammonium methyls
have to be equivalenced as well... Charge equivalecing seems to be
correct for RESP charges (although I did not check carefully) but not
for AM1-BCC. Why ?
regards, Francois
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Received on Mon Jul 06 2009 - 08:45:23 PDT
