Bandstructure and DoS calculation

Some basic understanding that deserved to be mentioned here:

1. Bandstructure calculation requires the system has translational invariance, which means the system should be a infinite system with certain lattice symmetry, otherwise there is now meaning for the definition of momentum .  So basically, we should calculate the bandstructure of the studied system in a 'lead' or at least should treat it as a lead.

2 DoS is by the same argument should be calculate inside a lead. And the system should not be 'finalize()' before your calculation of DoS or bandstructure.