How to print and save the oscillator strengths ?

Dear Meiyuan,

I'm not sure I understand the question correctly. Do you want the one particle matrix element to get absolute intensities, or do you want to get the relative intensities between different many particle states?

Quanty does not calculate the oscillation strength between the many particle eigenstates, instead CreateSpectra($O_1$,$O_2$,$\psi$) calculates \begin{equation} \langle \psi | O_2^{\dagger} \frac{1}{(\omega + \mathrm{i} \Gamma/2 + E_0 - O_1)} O_2 | \psi \rangle, \end{equation} see the documentation on CreateSpectra.

If you want the oscillation strength between the many body eigenstates you need to diagonalise the full final state Hamiltonian, which is a much harder task. You can always calculate the spectrum with very small broadening (and many points in the energy) to get something similar to a stick figure.

For the one particle matrix elements you can calculate expectation values between the radial wave functions. The tutorials on Monday on our last workshop show you how to work with the radial functions and calculate matrix elements.

Best wishes, Maurits

Hi Meiyuan,

Compared to codes like Orca or Molcas you don't get the “stick” spectrum, but a convoluted one. As Maurits said, you can use a smaller Gamma for the Lorentzian function to get something that looks like one.

Regarding the differences between what you see in Crispy and Quanty, the spectrum calculated in the interface is shifted to approximately come into the window of the experimental one. This is needed because, like all calculations, you don't get the spectrum on an absolute scale. Regarding broadening, I only implemented the Gaussian broadening in Crispy, and in all my tests, the results were identical to Quanty. If you still see differences, take out the Gaussian broadening in Crispy, and you should get identical spectra (aside from the shift).

Marius