[gmx-users] itp file using Gromos96 parameters

[Erik Lindahl]

Alan Wilter Sousa da Silva wrote:
> Hi Anton,
> 
> 	Thanks a lot!
> 	However I have a few more doubts.
> 
> 	In file ffG43a1bon.itp we have for Gromos bond-angle parameters:
> 
> #define ga_1         90.00      420.00
> ; NR(heme)  -  FE  -  NR(heme)  100
> ;
> etc...
> 
> 	As I believe, grompp will read #define ga_? line with its
> parameters (for ga_1: angle = 90.00 and constant = 420.00).
> 	My Gromos96 parameters for constant are in other unit system (I
> think) and correspond to the last value in the commented line, for ga_1:
> ; NR(heme)  -  FE  -  NR(heme)  100
> so constant = 100.
> 
> 	 What is constant according to this table?  How can I achieve
> these values, since I cannot see a correspondence?
> 

Gromos users kcal/mol while Gromacs adheres to the SI standard system 
and thus uses kJ/mol. We always use nm for lenght to, while a lot of 
other programs use AA...

Instead of 420 it should actually be 4.184*100, but 100 is only an 
order-of-magnitude guess in Gromos anyway...


Cheers,

Erik