[gmx-users] How to convert C6&C12 from GROMOS54a7 to sigma&epsilon for OPLSAA

Ming Tang m21.tang at qut.edu.au
Fri Aug 18 09:43:27 CEST 2017

Dear all,

I want to calculate sigma&epsilon for OPLSAA.ff from C6&C12 developed based on GROMOS54a7.ff.

>From the manual, I got the equations:

C12 = Sigma^(6)*C6
C6 = 4*sigma^(6)*epsilon
However, I found sigma and epsilon are different in OPLSAA and AMBER, and that C6&C12 from GROMOS and sigma&epsilon from OPLSAA do not match these equations. Could anybody give me some guidance?


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