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  2. Stefan problem - Wikipedia

    en.wikipedia.org/wiki/Stefan_problem

    Additionally, the solution of the Cahn–Hilliard equation for a binary mixture is reasonably comparable with the solution of a Stefan problem. [11] In this comparison, the Stefan problem was solved using a front-tracking, moving-mesh method with homogeneous Neumann boundary conditions at the outer boundary. Also, Stefan problems can be applied ...

  3. Harpoon reaction - Wikipedia

    en.wikipedia.org/wiki/Harpoon_reaction

    A harpoon reaction is a type of chemical reaction, first proposed by Michael Polanyi in 1920, [1] [2] whose mechanism (also called the harpooning mechanism) involves two neutral reactants undergoing an electron transfer over a relatively long distance to form ions that then attract each other closer together. [3]

  4. Reaction–diffusion system - Wikipedia

    en.wikipedia.org/wiki/Reaction–diffusion_system

    Reaction–diffusion systems are naturally applied in chemistry. However, the system can also describe dynamical processes of non-chemical nature. Examples are found in biology, geology and physics (neutron diffusion theory) and ecology. Mathematically, reaction–diffusion systems take the form of semi-linear parabolic partial differential ...

  5. Master equation - Wikipedia

    en.wikipedia.org/wiki/Master_equation

    A quantum master equation is a generalization of the idea of a master equation. Rather than just a system of differential equations for a set of probabilities (which only constitutes the diagonal elements of a density matrix ), quantum master equations are differential equations for the entire density matrix, including off-diagonal elements.

  6. Bell–Evans–Polanyi principle - Wikipedia

    en.wikipedia.org/wiki/Bell–Evans–Polanyi...

    The activation energy may be used to characterize the kinetic rate parameter of a given reaction through application of the Arrhenius equation. The Evans–Polanyi model assumes that the pre-exponential factor of the Arrhenius equation and the position of the transition state along the reaction coordinate are the same for all reactions ...

  7. Simon problems - Wikipedia

    en.wikipedia.org/wiki/Simon_problems

    In mathematics, the Simon problems (or Simon's problems) are a series of fifteen questions posed in the year 2000 by Barry Simon, an American mathematical physicist. [ 1 ] [ 2 ] Inspired by other collections of mathematical problems and open conjectures, such as the famous list by David Hilbert , the Simon problems concern quantum operators . [ 3 ]

  8. Solvated electron - Wikipedia

    en.wikipedia.org/wiki/Solvated_electron

    A solvated electron is a free electron in a solution, in which it behaves like an anion. [1] An electron's being solvated in a solution means it is bound by the solution. [ 2 ] The notation for a solvated electron in formulas of chemical reactions is "e − ".

  9. Inductive effect - Wikipedia

    en.wikipedia.org/wiki/Inductive_effect

    In Organic chemistry, the inductive effect in a molecule is a local change in the electron density due to electron-withdrawing or electron-donating groups elsewhere in the molecule, resulting in a permanent dipole in a bond. [1] It is present in a σ (sigma) bond, unlike the electromeric effect which is present in a π (pi) bond.