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Molecular modelling encompasses all methods, theoretical and computational, used to model or mimic the behaviour of molecules. [1] The methods are used in the fields of computational chemistry, drug design, computational biology and materials science to study molecular systems ranging from small chemical systems to large biological molecules and material assemblies.
The McCabe–Thiele method is a technique that is commonly employed in the field of chemical engineering to model the separation of two substances by a distillation column. [1] [2] [3] It uses the fact that the composition at each theoretical tray is completely determined by the mole fraction of one of the two components.
Phase-field models are usually constructed in order to reproduce a given interfacial dynamics. For instance, in solidification problems the front dynamics is given by a diffusion equation for either concentration or temperature in the bulk and some boundary conditions at the interface (a local equilibrium condition and a conservation law), [14] which constitutes the sharp interface model.
Since its adoption into the International System of Units in 1971, numerous criticisms of the concept of the mole as a unit like the metre or the second have arisen: the number of molecules, etc. in a given amount of material is a fixed dimensionless quantity that can be expressed simply as a number, not requiring a distinct base unit; [ 5 ] [ 24 ]
VLE of the mixture of chloroform and methanol plus NRTL fit and extrapolation to different pressures. The non-random two-liquid model [1] (abbreviated NRTL model) is an activity coefficient model introduced by Renon and Prausnitz in 1968 that correlates the activity coefficients of a compound with its mole fractions in the liquid phase concerned.
A problem with rigid bonds and holes is that systems with arbitrary angles could not be built. This can be overcome with flexible bonds, originally helical springs but now usually plastic. This also allows double and triple bonds to be approximated by multiple single bonds. A modern plastic ball and stick model. The molecule shown is proline
Once a refinement has been completed the results should be checked to verify that the chosen model is acceptable. generally speaking, a model is acceptable when the data are fitted within experimental error, but there is no single criterion to use to make the judgement. The following should be considered.
The situational theory of problem solving attempts to explain why and how an individual communicates during a problematic situation. The situational theory of problem solving (STOPS) was proposed by Jeong-Nam Kim and James E. Grunig in 2011 though their article “problem solving and communicative action: A situational theory of problem solving.”