In mathematics and applied mathematics, perturbation theory comprises methods for finding an approximate solution to a problem, by starting from the exact...

In quantum mechanics, perturbation theory is a set of approximation schemes directly related to mathematical perturbation for describing a complicated...

Møller–Plesset perturbation theory (MP) is one of several quantum chemistry post-Hartree–Fock ab initio methods in the field of computational chemistry...

cosmological perturbation theory is the theory by which the evolution of structure is understood in the Big Bang model. Cosmological perturbation theory may be...

Chiral perturbation theory (ChPT) is an effective field theory constructed with a Lagrangian consistent with the (approximate) chiral symmetry of quantum...

represented by a Feynman diagram according to perturbation theory in quantum mechanics. Quantum field theory emerged from the work of generations of theoretical...

In mathematics, variational perturbation theory (VPT) is a mathematical method to convert divergent power series in a small expansion parameter, say s...

Look up perturbation or perturb in Wiktionary, the free dictionary. Perturbation or perturb may refer to: Perturbation theory, mathematical methods that...

without derivatives. This means that one can manage this theory only by perturbation theory with small nonlinearities.[citation needed] Note that the...

straightforwardly defined using the techniques of perturbation theory, but it is not known in general how to define string theory nonperturbatively. It is also not clear...

Frontier molecular orbital theory Ligand field theory (MO theory for transition metal complexes) Møller–Plesset perturbation theory Quantum chemistry computer...

In solid-state physics, the k·p perturbation theory is an approximated semi-empirical approach for calculating the band structure (particularly effective...

the Stark effect in his third paper on quantum theory (in which he introduced his perturbation theory), once in the manner of the 1916 work of Epstein...

In mathematics, a singular perturbation problem is a problem containing a small parameter that cannot be approximated by setting the parameter value to...

In mathematics and electronics, cavity perturbation theory describes methods for derivation of perturbation formulae for performance changes of a cavity...

theory — Perturbation theory — Potential theory — Probability theory — Ramsey theory — Rational choice theory — Representation theory — Ring theory —...

In mathematics, an eigenvalue perturbation problem is that of finding the eigenvectors and eigenvalues of a system A x = λ x {\displaystyle Ax=\lambda...

theories used for these types of equations of state are the Barker-Henderson perturbation theory and the Weeks–Chandler–Andersen perturbation theory....

Causal perturbation theory is a mathematically rigorous approach to renormalization theory, which makes it possible to put the theoretical setup of perturbative...

renormalization of the theory. When the running coupling of the theory is small enough, then all required quantities may be computed in perturbation theory. Quantization...

classical piston theory is a powerful aerodynamic tool. From the use of the momentum equation and the assumption of isentropic perturbations, one obtains...

cases the approximation only applies after arrival at that orbit) Perturbation theory comprises mathematical methods that are used to find an approximate...

D'Hoker, Eric & Phong, D. H. (Oct 1988). "The geometry of string perturbation theory". Rev. Mod. Phys. 60 (4). American Physical Society: 917–1065. Bibcode:1988RvMP...

background. In this sense, string perturbation theory exhibits exactly the features one would expect of a perturbation theory that may exhibit a strong dependence...

motions under small perturbations. The theorem partly resolves the small-divisor problem that arises in the perturbation theory of classical mechanics...

density contributes a term in the gradient of the density. In a perturbation theory approach the direct correlation function is given by the sum of the...

respected by the theory. An example is the spectral line splitting in the Zeeman effect, due to a magnetic interaction perturbation in the Hamiltonian...

provides access to field configurations that are not accessible to perturbation theory, such as solitons. Similarly, non-trivial vacuum states can be identified...

a region of free space that has been divided into a lattice. k·p perturbation theory is a technique that allows a band structure to be approximately described...

Complete active space perturbation theory (CASPTn) is a multireference electron correlation method for computational investigation of molecular systems...