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  2. Dirac delta function - Wikipedia

    en.wikipedia.org/wiki/Dirac_delta_function

    On a locally compact Hausdorff space X, the Dirac delta measure concentrated at a point x is the Radon measure associated with the Daniell integral on compactly supported continuous functions φ. [34] At this level of generality, calculus as such is no longer possible, however a variety of techniques from abstract analysis are available.

  3. Born–Haber cycle - Wikipedia

    en.wikipedia.org/wiki/Born–Haber_cycle

    ΔH latt corresponds to U L in the text. The downward arrow "electron affinity" shows the negative quantity –EA F, since EA F is usually defined as positive. The enthalpy of formation of lithium fluoride (LiF) from its elements in their standard states (Li(s) and F 2 (g)) is modeled in five steps in the diagram: Atomization enthalpy of lithium

  4. Gibbs–Helmholtz equation - Wikipedia

    en.wikipedia.org/wiki/Gibbs–Helmholtz_equation

    The definition of the Gibbs function is = + where H is the enthalpy defined by: = +. Taking differentials of each definition to find dH and dG, then using the fundamental thermodynamic relation (always true for reversible or irreversible processes): = where S is the entropy, V is volume, (minus sign due to reversibility, in which dU = 0: work other than pressure-volume may be done and is equal ...

  5. Delta-functor - Wikipedia

    en.wikipedia.org/wiki/Delta-functor

    For each short exact sequence as above, there is a long exact sequence; For each morphism of short exact sequences and for each non-negative n, the induced square . is commutative (the δ n on the top is that corresponding to the short exact sequence of M's whereas the one on the bottom corresponds to the short exact sequence of N's).

  6. Helmholtz free energy - Wikipedia

    en.wikipedia.org/wiki/Helmholtz_free_energy

    F is the Helmholtz free energy (sometimes also called A, particularly in the field of chemistry) (SI: joules, CGS: ergs), U is the internal energy of the system (SI: joules, CGS: ergs), T is the absolute temperature of the surroundings, modelled as a heat bath, S is the entropy of the system (SI: joules per kelvin, CGS: ergs per kelvin).

  7. Hessian matrix - Wikipedia

    en.wikipedia.org/wiki/Hessian_matrix

    The above rules stating that extrema are characterized (among critical points with a non-singular Hessian) by a positive-definite or negative-definite Hessian cannot apply here since a bordered Hessian can neither be negative-definite nor positive-definite, as = if is any vector whose sole non-zero entry is its first.

  8. Helmholtz decomposition - Wikipedia

    en.wikipedia.org/wiki/Helmholtz_decomposition

    The Helmholtz decomposition in three dimensions was first described in 1849 [9] by George Gabriel Stokes for a theory of diffraction. Hermann von Helmholtz published his paper on some hydrodynamic basic equations in 1858, [10] [11] which was part of his research on the Helmholtz's theorems describing the motion of fluid in the vicinity of vortex lines. [11]

  9. Positive and negative parts - Wikipedia

    en.wikipedia.org/wiki/Positive_and_negative_parts

    Note that both f + and f − are non-negative functions. A peculiarity of terminology is that the 'negative part' is neither negative nor a part (like the imaginary part of a complex number is neither imaginary nor a part). The function f can be expressed in terms of f + and f − as = +.