[gmx-users] distance and energy measure

[hugo verli]

Is there any command in gromacs to measure the average and/or variation 
distance between two atoms in a molecular dynamics trajectory? And about the 
interaction energy between a inhibitor and the enzyme? In this last case, is 
there any way to measure the interaction energy between the ligand and each 
aminoacid residue?

Thanks for your help,

Hugo.