Default observer interval should be len(atoms)
Can we please set the default observeration intervals to len(atoms)?
Everytime I make some testing for Mchammer I get things like
mctrial potential acceptance_ratio sro_Cl_1 sro_Cl_2
0 0 0.619185 0.000000 1.0 1.0
1 128 NaN NaN 1.0 1.0
2 130 0.386255 0.676923 NaN NaN
3 256 NaN NaN 1.0 1.0
4 260 0.120788 0.607692 NaN NaN
(Maybe better is len(active_sites)
but I will settle for len(atoms))