simple degeneracy
11Molecular orbital — See also: Molecular orbital theory In chemistry, a molecular orbital (or MO) is a mathematical function describing the wave like behavior of an electron in a molecule. This function can be used to calculate chemical and physical properties such… …
12Perturbation theory — This article describes perturbation theory as a general mathematical method. For perturbation theory as applied to quantum mechanics, see perturbation theory (quantum mechanics). Perturbation theory comprises mathematical methods that are used to …
13Particle in a box — In physics, the particle in a box (also known as the infinite potential well or the infinite square well) is a problem consisting of a single particle inside of an infinitely deep potential well, from which it cannot escape, and which loses no… …
14Catastrophe theory — This article refers to the study of dynamical systems. For other meanings, see catastrophe. In mathematics, catastrophe theory is a branch of bifurcation theory in the study of dynamical systems; it is also a particular special case of more… …
15Group (mathematics) — This article covers basic notions. For advanced topics, see Group theory. The possible manipulations of this Rubik s Cube form a group. In mathematics, a group is an algebraic structure consisting of a set together with an operation that combines …
16Black hole — For other uses, see Black hole (disambiguation). Simulated view of a black hole (center) in front of the Large Magellanic Cloud. Note the gravitat …
17Pauli exclusion principle — The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925. It states that no two identical fermions may occupy the same quantum state simultaneously . A more rigorous statement of this principle is that …
18Shell model — In nuclear physics, the nuclear shell model is a model of the atomic nucleus which uses the Pauli principle to describe the structure of the nucleus in terms of energy levels. The model was developed in 1949 following independent work by several… …
19Quantum harmonic oscillator — The quantum harmonic oscillator is the quantum mechanical analogue of the classical harmonic oscillator. It is one of the most important model systems in quantum mechanics because an arbitrary potential can be approximated as a harmonic potential …
20Partition function (statistical mechanics) — For other uses, see Partition function (disambiguation). Partition function describe the statistical properties of a system in thermodynamic equilibrium. It is a function of temperature and other parameters, such as the volume enclosing a gas.… …
