[gmx-users] Problem with g_rdf /option com

[OZGE ENGIN]

Hi,

I want to get the radial distribution of my system which is composed of a box of capped alanine residues (CAR). In this respect, I used g_rdf command with -com option. I chose one of the CAR s as the first, and the others as the second group. In manual, for -com option, it is written that the center of mass is chosen only for the first group. 

Does it mean that for the second group all the atoms are taken into consideration? If so, is there any option for taking the center of masses of molecules in the second group? 

Thanks

Ozge.