[gmx-users] using two different combination rules for the LJ potentia

[Ana West]

Thank you so much for the kind reply. I made a mistake in my previous  
posting - I am dealing with combination rule 1 and the combination  
rule 2. Initially I converted the parameters according to section  
5.3.3 of the manual and when I did some tests to verify my  
force-field, the minimum of the potential well seemed fine but the  
repulsive part of the potential was not steep enough. The conversion  
did not seem to work for me.

Is there sort of a qualitative way of knowing when the conversion from  
section 5.3.3 fails? (like maybe it fails when one has relatively high  
partial charges ?!?1). If I would know that then maybe I will get more  
lucky with the conversions for the other molecule and keep the  
combination rules for the one for which I know the conversion  
parameters fail.

Thank you so much! Your reply helped me.

Ana