Exciton magnetic moment

Overview - Off-diagonal Exciton Spin Matrix Elements

This is a patch designed to calculate the spin matrix elements of wavefunction along the x, y and z directions. The first part calculated these in the single-particle level, by multiplying the electronic wavefunctions read from BerkeleyGW hdf5 format, with the Pauli matrices.

The second part then reads the calculated electronic single particle spin elements and multiplies them with the excitonic wavefunctions calculated in BerkeleyGW with the absorption code and generate the spin matrix elements for excitons.

In both the electronic and exciton parts, the calculation includes the determination of off-diagonal elements. These off-diagonal elements can be particularly useful in scenarios involving degenerate states. Both calculations are performed using Python scripts.

Please adhere to the steps detailed in the notebook in the BSE/MagneticSpin directory. Currently, the scripts focus solely on calculating the spin magnetic moment elements, with plans to incorporate the orbital magnetic moment part in subsequent updates.