How to Choose properly the E0 and E1 for using Energy interval method

[weixiang]

Dear Quantumwise Experts,
In calculating the Inelastic transmission spectrum, there is a speed-up method called "Phonon Energy Intervals" that instead of calculating explicitly all the 3N phonon modes of the device, it groups the 3N modes into M energy intervals and we will only need to calculate these M new effective phonon modes. So that it is much faster.
My question is to choose E₀ and E₁, how to ensure the energy interval [E₀,E₁] span that of the phonon modes of the calculated dynamical matrix.  Is there a way to check the relevant information from the dynamical matrix object?

[Petr Khomyakov]

I guess the only way of checking it is to calculate phonon density of states or phonon band structure, using the dynamical matrix.