Re: How the partial charges be computed in CVFF force field

[Oliver Hucke <Oliver.Hucke : at : physchem.uni-freiburg.de>]

Dear Song Yunlong,
 I have used InsightII in conjunction with the charmm forcefield and
 Delphi to perform electrostatics calculations.
 In this case the partial charges are obtained from the topology file of
 the forcefield. It should be the same with cvff? In the directory
 [Insight instalation path]/I2000/irix6m4/biosym_lib/
 I can find a file cvff.rlb which seems to contain the atomic partial
 charges...
 Best,
 Oliver
 > Dear all the CCLers:
 >     I am a user of InsightII of Accelrys(former MSI). When I perform
 comutations,such as molecular minization or dynamics,I often use CVFF force
 field. I always use FF (Force Field). This command is activated on the left side
 by clicking on the FF button. Then select Forcefield/Potentials and make sure
 that all of the settings as follows.
 >             Potential Action [Fix]
 >
 >             Partial Charge Action [Fix]
 >
 >             Formal Charge Action [Fix or Accept]
 >
 >     My question is how the partial charges of my molecules are computed? In
 my opinion,the partial charges are part of the CVFF force field. When CVFF is
 used, the partial charges are automatically loaded from the system file. This is
 quite different from MM2 (Tripos) method which often calculate partial charge
 through Gasteiger-Huckel method for small molecules.Is this so? I have referred
 several papers, but find no how the charges are computed.
 >
 >     I am eager to get any helpful suggestions.
 >
 >     Thank you in advance!
 >
 > Song Yunlong
 > songyunlong : at : 263.net
 >
 --
 ____________________________________________________________________________
 Oliver Hucke
 Inst. fuer Physikalische Chemie II
 Universitaet Freiburg
 Albertstr. 23a
 D-79104 Freiburg
 Tel. :  +49-761-203-5130 (/-6179)
 Fax. :  +49-761-203-6189
 email:  Oliver.Hucke : at : physchem.uni-freiburg.de
 ____________________________________________________________________________