### BSE Hamiltonian in spin-polarized semiconducting system

Posted:

**Tue Jan 02, 2018 2:05 pm**Dear users and developers:

When solving the BSE in Bloch space, we know that yambo uses single electron-hole transitions as the basis to build BSE Hamiltonian.

So, for a spin-polarized semiconductor, will the single electron-hole transitions with flipped spin (e.g., the hole is from a spin-up valence band and the electron is from a spin-down conducting band) be included in the basis when constructing BSE Hamiltonian ?

From the theory of BSE, the inclusion of these spin-flipped electron-hole transitions is quite natural, and at sometime it's also necessary (e.g., for the description of singlet-triplet splitting). But by checking the total number of eigenvalues in "exc_E_sorted" file created by "ypp -e s", it seems that yambo constructs and diagonalizes BSE Hamiltonian for spin-up and spin-down subspace respectively, and the transitions between different spin are not includedâ€¦â€¦

I will be very grateful that if anyone can give me a final confirmation.

Thank you !

When solving the BSE in Bloch space, we know that yambo uses single electron-hole transitions as the basis to build BSE Hamiltonian.

So, for a spin-polarized semiconductor, will the single electron-hole transitions with flipped spin (e.g., the hole is from a spin-up valence band and the electron is from a spin-down conducting band) be included in the basis when constructing BSE Hamiltonian ?

From the theory of BSE, the inclusion of these spin-flipped electron-hole transitions is quite natural, and at sometime it's also necessary (e.g., for the description of singlet-triplet splitting). But by checking the total number of eigenvalues in "exc_E_sorted" file created by "ypp -e s", it seems that yambo constructs and diagonalizes BSE Hamiltonian for spin-up and spin-down subspace respectively, and the transitions between different spin are not includedâ€¦â€¦

I will be very grateful that if anyone can give me a final confirmation.

Thank you !