This for the PartialReinsertionProbability move, where only a few atoms are regrown and the others are left fixed.
So, in this case there are 4 config move defined (and you see 5 lines). For each line you have the number of fixed atoms, and the the list of the fixed atom ids.
The other atoms are regrown using CBMC. This move has high efficiency, because the molecule is already present and is only partially regrown.
Note that in CBMC all branches need to be grown at the same time, so you can not keep more than one branch fixed (in a branched molecule).
So, in this case there are 4 config move defined (and you see 5 lines). For each line you have the number of fixed atoms, and the the list of the fixed atom ids.
The other atoms are regrown using CBMC. This move has high efficiency, because the molecule is already present and is only partially regrown.
Note that in CBMC all branches need to be grown at the same time, so you can not keep more than one branch fixed (in a branched molecule).