In very recent years, exciton physics has been intensively explored as the emergence of 2D materials. Exciton is a bound electron-hole pair and is bosonic, namely hosting an integer spin.
My first question is what the integer spin is? We all know the spin of an electron is $\dfrac{1}{2}$ and the hole will hold a positive charge compared to the kicked electron. Can we consider that the spin of the hole will be $-\dfrac{1}{2}$ and the exciton holds an integer spin $0$.
My second question is how the formation of the exciton is affected by the spin of electrons? For example, the following figure from this paper indicates that the spin is closely related to the formation of the exciton.
My third question is how can we demonstrate these spin-related exciton landscapes with first-principles calculations?