expectation value
31expected value — Statistics, Math. See mathematical expectation. [1945 50] * * * …
32Feynman diagram — The Wick s expansion of the integrand gives (among others) the following termNarpsi(x)gamma^mupsi(x)arpsi(x )gamma^ upsi(x )underline{A mu(x)A u(x )};,whereunderline{A mu(x)A u(x )}=int{d^4pover(2pi)^4}{ig {mu u}over k^2+i0}e^{ k(x x )}is the… …
33Partition function (mathematics) — The partition function or configuration integral, as used in probability theory, information science and dynamical systems, is an abstraction of the definition of a partition function in statistical mechanics. It is a special case of a… …
34Casimir effect — Casimir forces on parallel plates Casimir forces on parallel pl …
35Higgs mechanism — The Higgs mechanism is spontaneous symmetry breaking in a gauge theory.It considers all of space filled with a quantum field, called the Higgs field, the interaction with which prevents certain forces from propagating over long distances. Part of …
36Uncertainty principle — In quantum physics, the Heisenberg uncertainty principle states that locating a particle in a small region of space makes the momentum of the particle uncertain; and conversely, that measuring the momentum of a particle precisely makes the… …
37Normal order — For other uses, see Normal order (disambiguation). In quantum field theory a product of quantum fields, or equivalently their creation and annihilation operators, is usually said to be normal ordered (also called Wick order) when all creation… …
38STO-nG basis sets — STO nG basis sets are the minimal basis sets, where n represents the number of primitive Gaussian functions comprising a single basis set. For minimal basis sets, the core and valence orbitals are represented by same number primitive Gaussian fu …
39Path integral formulation — This article is about a formulation of quantum mechanics. For integrals along a path, also known as line or contour integrals, see line integral. The path integral formulation of quantum mechanics is a description of quantum theory which… …
40Multipole moments — are the coefficients of a series expansion of a potential due to continuous or discrete sources (e.g., an electric charge distribution). A multipole moment usually involves powers (or inverse powers) of the distance to the origin, as well as some …
