[gmx-users] OPLS-AA Charge Calculation

TJ Piggot t.piggot at bristol.ac.uk
Wed Aug 30 14:21:02 CEST 2006

Hi all,

I am trying to calculate partial charges of a ligand for the OPLS-AA/L 
forcefield. I have searched the mailing lists and literature and would like 
to confirm that the approach i am going to take is a sensible and accurate 

Firstly i take an all atom structure of the ligand and minimise in 
gaussian03 using the RHF method and 6-31G* basis set (is this a suitable 
level of theory for my charged ligand of 43 atoms?).

Then i calculate the electrostatic potential using the CHelpG method and 
output it on a grid.

Then use a two stage RESP fitting to calculate the charges.

Thanks for any input you have on this approach

Tom Piggot

TJ Piggot
t.piggot at bristol.ac.uk

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