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  2. Hellmann–Feynman theorem - Wikipedia

    en.wikipedia.org/wiki/HellmannFeynman_theorem

    The HellmannFeynman theorem is actually a direct, and to some extent trivial, consequence of the variational principle (the Rayleigh–Ritz variational principle) from which the Schrödinger equation may be derived. This is why the HellmannFeynman theorem holds for wave-functions (such as the Hartree–Fock wave-function) that, though not ...

  3. Feynman–Kac formula - Wikipedia

    en.wikipedia.org/wiki/Feynman–Kac_formula

    The Feynman–Kac formula, named after Richard Feynman and Mark Kac, establishes a link between parabolic partial differential equations and stochastic processes.In 1947, when Kac and Feynman were both faculty members at Cornell University, Kac attended a presentation of Feynman's and remarked that the two of them were working on the same thing from different directions. [1]

  4. Infinitesimal generator (stochastic processes) - Wikipedia

    en.wikipedia.org/wiki/Infinitesimal_generator...

    The Kolmogorov forward equation in the notation is just =, where is the probability density function, and is the adjoint of the infinitesimal generator of the underlying stochastic process. The Klein–Kramers equation is a special case of that.

  5. Variational principle - Wikipedia

    en.wikipedia.org/wiki/Variational_principle

    HellmannFeynman theorem; Gauss's principle of least constraint and Hertz's principle of least curvature; Hilbert's action principle in general relativity, leading to the Einstein field equations. Palatini variation; Hartree–Fock method; Density functional theory; Gibbons–Hawking–York boundary term; Variational quantum eigensolver

  6. List of theorems - Wikipedia

    en.wikipedia.org/wiki/List_of_theorems

    HellmannFeynman theorem ; Helly–Bray theorem (probability theory) Helly's selection theorem (mathematical analysis) Helly's theorem (convex sets) Helmholtz theorem (classical mechanics) Helmholtz's theorems ; Herbrand's theorem ; Herbrand–Ribet theorem (cyclotomic fields) Higman's embedding theorem (group theory)

  7. Surface hopping - Wikipedia

    en.wikipedia.org/wiki/Surface_hopping

    The last equation is derived using the Hellmann-Feynman theorem. The brackets show that the integral is done only over the quantum degrees of freedom. Choosing only one adiabatic surface is an excellent approximation if the difference between the adiabatic surfaces is large for energetically accessible regions of . When this is not the case ...

  8. Perturbation theory (quantum mechanics) - Wikipedia

    en.wikipedia.org/wiki/Perturbation_theory...

    Whenever a state derivative is encountered, resolve it by inserting the complete set of basis, then the Hellmann-Feynman theorem is applicable. Because differentiation can be calculated systematically, the series expansion approach to the perturbative corrections can be coded on computers with symbolic processing software like Mathematica .

  9. Standard Model - Wikipedia

    en.wikipedia.org/wiki/Standard_Model

    Interactions in the Standard Model. All Feynman diagrams in the model are built from combinations of these vertices. q is any quark, g is a gluon, X is any charged particle, γ is a photon, f is any fermion, m is any particle with mass (with the possible exception of the neutrinos), m B is any boson with mass. In diagrams with multiple particle ...