[gmx-users] default state of "energygrps" in .mdp file

[Agnivo Gosai]

Hello users

This might come off as a stupid question but I am afraid to admit that I am
confused.

What is the default state of "energygrps" in a GROMACS simulation ? I know
that I can write energygrps = System or energygrps =  A B etc. , but what
happens if I do not specifiy any "energygrps" in a .mdp file.

I checked the mdout.mdp generated during grompp+mdrun and found that
energygrps = (blank). In that case what is happening ? I use version 4.6.7
and also checked the manual but could not satisfy myself.

Kindly answer.

Thanks & Regards
Agnivo Gosai
Grad Student, Iowa State University.