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The Korringa–Kohn–Rostoker (KKR) method is used to calculate the electronic band structure of periodic solids.In the derivation of the method using multiple scattering theory by Jan Korringa [1] and the derivation based on the Kohn and Rostoker variational method, [2] the muffin-tin approximation was used. [3]
The Kramers–Heisenberg dispersion formula is an expression for the cross section for scattering of a photon by an atomic electron.It was derived before the advent of quantum mechanics by Hendrik Kramers and Werner Heisenberg in 1925, [1] based on the correspondence principle applied to the classical dispersion formula for light.
It relates the scattered wave function with the interaction that produces the scattering (the scattering potential) and therefore allows calculation of the relevant experimental parameters (scattering amplitude and cross sections). The most fundamental equation to describe any quantum phenomenon, including scattering, is the Schrödinger equation.
The following description follows the canonical way of introducing elementary scattering theory. A steady beam of particles scatters off a spherically symmetric potential V ( r ) {\displaystyle V(r)} , which is short-ranged, so that for large distances r → ∞ {\displaystyle r\to \infty } , the particles behave like free particles.
In scattering theory, the S-matrix is an operator mapping free particle in-states to free particle out-states (scattering channels) in the Heisenberg picture. This is very useful because often we cannot describe the interaction (at least, not the most interesting ones) exactly.
Let be a unital associative algebra.In its most general form, the parameter-dependent Yang–Baxter equation is an equation for (, ′), a parameter-dependent element of the tensor product (here, and ′ are the parameters, which usually range over the real numbers ℝ in the case of an additive parameter, or over positive real numbers ℝ + in the case of a multiplicative parameter).
Scattering theory is the theory of scattering events which can occur as well in quantum mechanics, classical electrodynamics or acoustics. The associated general mathematical frame bears the same name though its range of application may be larger.
K-theory involves the construction of families of K-functors that map from topological spaces or schemes, or to be even more general: any object of a homotopy category to associated rings; these rings reflect some aspects of the structure of the original spaces or schemes.