chi0: 1D "not supported"
chi0 raises errors if we try to do 1D:
if sum(self.pbc) == 1:
raise ValueError('1-D not supported atm.')
But the error is not raised close to the code which does not support 1D, so I don't know whether the error reflects reality or not.
We should find out what goes wrong in 1D, if anything (discussion required), and then the error should be triggered (if necessary) close to its cause.