[gmx-users] Re: charges

[Graham Smith]

Sometimes I have altered the charges by hand using, for example, the
differences between compounds containing corresponding charged and
neutral groups in the force-field files. 

I suppose the best thing would be to do a QM calculation, I think
there are quite a few packages available.  

I don't know very much about using any of them myself, but they
probably have their own user groups: 

Widely used, but expensive: 
Gaussian: www.gaussian.com
Jaguar: www.schrodinger.com

Free:
GAMESS-US: http://www.msg.ameslab.gov/GAMESS/dist.menu.html
NWChem: http://www.emsl.pnl.gov:2080/docs/nwchem/nwchem.html

Powerful (and free) but, they tell me, difficult to use:
http://www.kjemi.uio.no/software/dalton/dalton.html

I think the QM calculations start getting difficult if you have any
atoms heavier than the 2nd row of the periodic table. 

########################################################################

Dr. Graham R. Smith, 		       Department of Biological Sciences,  
Biomolecular Modelling Laboratory,     Biochemistry Building,              	
Cancer Research UK, 		       Imperial College of Science,        	
44 Lincoln's Inn Fields, 	        Technology & Medicine,             	
London WC2A 3PX,		       London SW7 2AZ,                     	
U.K. 				       U.K.                                	
Tel: +44-(0)20 7269 3348 	       Tel: +44-(0)20 7594 5737            	
email: graham.smith at cancer.org.uk	
URL: http://www.bmm.icnet.uk/~smithgr