The wave function in quantum physics is a mathematical description of the quantum state of an isolated quantum system. The wave function is a complex-valued probability amplitude from which it is possible to calculate the likelihood of a potential result of a measurement made on the system. The most common symbol for the wave function is the Greek letter Ψ. In general, the wave function is a function of space and time, i.e., Ψ = Ψ(x, y, z, t). The wave function is the central element of quantum theory, which can completely describe a quantum system. Wave function analysis is of great importance for studying the electronic structure characteristics of chemical systems (e.g. bonding type and strength, charge distribution, electron delocalization), molecular properties (e.g. reactivity, electrical conductivity, evaporation enthalpy, solubility), and interactions with the external environment (e.g. weak intermolecular interactions, electron-excited leap modes).