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Methylaluminoxane, commonly called MAO, is a mixture of organoaluminium compounds with the approximate formula (Al(CH 3)O) n. It is usually encountered as a solution in ( aromatic ) solvents , commonly toluene but also xylene , cumene , or mesitylene , [ 1 ] Used in large excess, it activates precatalysts for alkene polymerization.
PDF of the NN distances in an ideal gas. We want to calculate probability distribution function of distance to the nearest neighbor (NN) particle. (The problem was first considered by Paul Hertz; [1] for a modern derivation see, e.g.,. [2])
A force field is used to minimize the bond stretching energy of this ethane molecule.. Molecular mechanics uses classical mechanics to model molecular systems. The Born–Oppenheimer approximation is assumed valid and the potential energy of all systems is calculated as a function of the nuclear coordinates using force fields.
where δ i is the distance between atom i and either a reference structure or the mean position of the N equivalent atoms. This is often calculated for the backbone heavy atoms C, N, O, and C α or sometimes just the C α atoms. Normally a rigid superposition which minimizes the RMSD is performed, and this minimum is returned.
Quantity (common name/s) (Common) symbol/s Defining equation SI units Dimension Number of atoms N = Number of atoms remaining at time t. N 0 = Initial number of atoms at time t = 0
However, if the range of the interatomic potential is finite, i.e. the potentials () above some cutoff distance , the summing can be restricted to atoms within the cutoff distance of each other. By also using a cellular method for finding the neighbours, [ 1 ] the MD algorithm can be an O(N) algorithm.
Each cut-point can be recovered for future size-respective chemical analyses. This technique has been used for decades in the air pollution control industry (data used for design of control devices). This technique determines particle size as a function of settling velocity in an air stream (as opposed to water, or some other liquid).
In chemistry, the molar absorption coefficient or molar attenuation coefficient (ε) [1] is a measurement of how strongly a chemical species absorbs, and thereby attenuates, light at a given wavelength. It is an intrinsic property of the species.