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Square antiprism. In geometry, the square antiprism is the second in an infinite family of antiprisms formed by an even-numbered sequence of triangle sides closed by two polygon caps. It is also known as an anticube. [1] If all its faces are regular, it is a semiregular polyhedron or uniform polyhedron .
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]
In chemistry, the square antiprismatic molecular geometry describes the shape of compounds where eight atoms, groups of atoms, or ligands are arranged around a central atom, defining the vertices of a square antiprism. [1] This shape has D 4d symmetry and is one of the three common shapes for octacoordinate transition metal complexes, along ...
Visualizing a Fischer projection. In chemistry, the Fischer projection, devised by Emil Fischer in 1891, is a two-dimensional representation of a three-dimensional organic molecule by projection. Fischer projections were originally proposed for the depiction of carbohydrates and used by chemists, particularly in organic chemistry and biochemistry.
Esophoria is an eye condition involving inward deviation of the eye, usually due to extra-ocular muscle imbalance. It is a type of heterophoria. Cause. Causes include: Refractive errors; Divergence insufficiency; Convergence excess; this can be due to nerve, muscle, congenital or mechanical anomalies.
Unit cell with water molecules, used to simulate flowing water. Periodic boundary conditions (PBCs) are a set of boundary conditions which are often chosen for approximating a large (infinite) system by using a small part called a unit cell. PBCs are often used in computer simulations and mathematical models. The topology of two-dimensional PBC ...
Whereas in the CHA model, those orbitals have no greater intrinsic freedom and therefore the correction treats all fragments equally. The errors inherent in either BSSE correction disappear more rapidly than the total value of BSSE in larger basis sets. See also. Basis set (chemistry) Quantum chemistry; Quantum chemistry computer programs
In concrete chemistry, ettringite is a hexacalcium aluminate trisulfate hydrate, of general formula when noted as oxides: 6CaO·Al 2 O 3 ·3SO 3 ·32H 2 O. or 3CaO·Al 2 O 3 ·3CaSO 4 ·32H 2 O. Ettringite is formed in the hydrated Portland cement system as a result of the reaction of tricalcium aluminate (C 3 A) with calcium sulfate, both ...
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.
In chemistry, the dodecahedral molecular geometry describes the shape of compounds where eight atoms or groups of atoms or ligands are arranged around a central atom defining the vertices of a snub disphenoid (also known as a trigonal dodecahedron). This shape has D 2d symmetry and is one of the three common shapes for octacoordinate transition ...