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Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
The Benesi–Hildebrand method is a mathematical approach used in physical chemistry for the determination of the equilibrium constant K and stoichiometry of non-bonding interactions. This method has been typically applied to reaction equilibria that form one-to-one complexes, such as charge-transfer complexes and host–guest molecular ...
Scherrer equation. The Scherrer equation, in X-ray diffraction and crystallography, is a formula that relates the size of sub- micrometre crystallites in a solid to the broadening of a peak in a diffraction pattern. It is often referred to, incorrectly, as a formula for particle size measurement or analysis. It is named after Paul Scherrer.
Eyring equation. The Eyring equation (occasionally also known as Eyring–Polanyi equation) is an equation used in chemical kinetics to describe changes in the rate of a chemical reaction against temperature. It was developed almost simultaneously in 1935 by Henry Eyring, Meredith Gwynne Evans and Michael Polanyi.
Viscosity depends strongly on temperature. In liquids it usually decreases with increasing temperature, whereas, in most gases, viscosity increases with increasing temperature. This article discusses several models of this dependence, ranging from rigorous first-principles calculations for monatomic gases, to empirical correlations for liquids.
Pitzer equations [1] are important for the understanding of the behaviour of ions dissolved in natural waters such as rivers, lakes and sea-water. [2] [3] [4] They were first described by physical chemist Kenneth Pitzer. [5] The parameters of the Pitzer equations are linear combinations of parameters, of a virial expansion of the excess Gibbs ...
In quantum chemistry and molecular physics, the Born–Oppenheimer (BO) approximation is the best-known mathematical approximation in molecular dynamics. Specifically, it is the assumption that the wave functions of atomic nuclei and electrons in a molecule can be treated separately, based on the fact that the nuclei are much heavier than the electrons.
Schröder's equation is an eigenvalue equation for the composition operator Ch that sends a function f to f(h(.)) . If a is a fixed point of h, meaning h(a) = a, then either Ψ (a) = 0 (or ∞) or s = 1. Thus, provided that Ψ (a) is finite and Ψ′ (a) does not vanish or diverge, the eigenvalue s is given by s = h′ (a) .