Point defects are used to control a variety of electronic and optical properties of materials, in which the concept of a charge state of a defect is oftentimes useful. The charge state of a defect is the relative charge that is localized at the defect site. Analogous to Kröger-Vink notation, we say that the defect has a negative charge state when additional electrons are localized at the defect site (i.e., an acceptor), a positive charge state when electrons are delocalized from the defect site (i.e., a donor), and a neutral 0 charge state otherwise. In phosphorus-doped silicon for example, it is typically understood that a P dopant (5 valence e -) donates an electron to the electron reservoir when substituting for Si (4 valence e -). Since an electron delocalizes from the P dopant in this scenario, we label the defect with a +1 charge state, denoted by a superscript as P +1