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  2. Density functional theory - Wikipedia

    en.wikipedia.org/wiki/Density_functional_theory

    The second HK theorem defines an energy functional for the system and proves that the ground-state electron density minimizes this energy functional. In work that later won them the Nobel prize in chemistry , the HK theorem was further developed by Walter Kohn and Lu Jeu Sham to produce Kohn–Sham DFT (KS DFT).

  3. Quizlet - Wikipedia

    en.wikipedia.org/wiki/Quizlet

    Quizlet's primary products include digital flash cards, matching games, practice electronic assessments, and live quizzes. In 2017, 1 in 2 high school students used Quizlet. [ 4 ] As of December 2021, Quizlet has over 500 million user-generated flashcard sets and more than 60 million active users.

  4. Time-dependent density functional theory - Wikipedia

    en.wikipedia.org/wiki/Time-dependent_density...

    The formal foundation of TDDFT is the Runge–Gross (RG) theorem (1984) [1] – the time-dependent analogue of the Hohenberg–Kohn (HK) theorem (1964). [2] The RG theorem shows that, for a given initial wavefunction, there is a unique mapping between the time-dependent external potential of a system and its time-dependent density.

  5. Squirrel AI - Wikipedia

    en.wikipedia.org/wiki/Squirrel_AI

    For example, middle school mathematics is broken into over 10,000 points such as rational numbers, the properties of a triangle, and the Pythagorean theorem. Each point is linked to related items, forming a "knowledge graph". Each knowledge point is addressed by videos, examples and practice problems.

  6. Fourier transform - Wikipedia

    en.wikipedia.org/wiki/Fourier_transform

    Plancherel's theorem makes it possible to extend the Fourier transform, by a continuity argument, to a unitary operator on L 2 (R). On L 1 ( R ) ∩ L 2 ( R ) , this extension agrees with original Fourier transform defined on L 1 ( R ) , thus enlarging the domain of the Fourier transform to L 1 ( R ) + L 2 ( R ) (and consequently to L p ( R ...

  7. Complement (group theory) - Wikipedia

    en.wikipedia.org/wiki/Complement_(group_theory)

    In mathematics, especially in the area of algebra known as group theory, a complement of a subgroup H in a group G is a subgroup K of G such that = = {:,} = {}. Equivalently, every element of G has a unique expression as a product hk where h ∈ H and k ∈ K.

  8. Riesz representation theorem - Wikipedia

    en.wikipedia.org/wiki/Riesz_representation_theorem

    Riesz representation theorem — Let be a Hilbert space whose inner product , is linear in its first argument and antilinear in its second argument and let := , be the corresponding physics notation.

  9. Graph isomorphism problem - Wikipedia

    en.wikipedia.org/wiki/Graph_isomorphism_problem

    At the same time, isomorphism for many special classes of graphs can be solved in polynomial time, and in practice graph isomorphism can often be solved efficiently. [ 3 ] [ 4 ] This problem is a special case of the subgraph isomorphism problem , [ 5 ] which asks whether a given graph G contains a subgraph that is isomorphic to another given ...