#210 Excited states from Chebychev method

[Burkhard Schmidt]

Extend the Chebychev propagation for imaginary time propagation such that it not only calculates ground states, but also (the first few, at least) excited states. This can be done by projection methods, see preliminary "experiments" in the MolVib/H3+/exc1|2 demos.

[Burkhard Schmidt]

Essentially fixed this today, at least for hamilt.coupling.n_eqs=1, which is quite nice already. And it fixes the MolVib/H3+ demo.

However, for hamilt.coupling.n_eqs>1 the imaginary time propagator (cheby_imag) is still throwing an error message. But this shouldn't be too difficult to fix ... one day ;-)

On that occasion, the scalar products could be calculated using
coeff = wave.braket ( psi.bound{ii}, psi.dvr{1} );

Perhaps something similar for the normalization ?!?