Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Dynamic definition

In C++, the static variables and operations of a class can be thought of as forming a class object but with limited features. There is no metaclass to which class-object classes belong and no dynamic definition of new classes. [Pg.175]

The conditions (133.HI) mean that the tunneling through the adiabatic potential barriers (99.HI) is neglected however, the non-adiabatic transitions from a lower to a higher electronic state are not excluded. The reflexion effects due to the reaction path curvature may be simply included in the dynamical definition (121.11) of the reaction coordinate. An adiabatic separation of that coordinate may be also used as an approximation at these conditions. Then, the "transmission coefficient — 1 takes into account only sudden changes... [Pg.169]

For quasi-static measurements such as illustrated in Figure 8.2, the glass transition temperature, Tg, is often taken at the maximum rate of turndown of the modulus at the elbow, where E = lO Pa. Often the glass transition temperature is defined as the temperature where the thermal expansion coefficient (Section 8.3) undergoes a discontinuity. (Enthalpic and dynamic definitions are given in Section 8.2.9. Other, more precise definitions are given in Section 8.5.)... [Pg.358]

This more conventional use of the term steady state, which simply connotes time-independence for N(E), is fundamentally different from the dynamical definition that arises in the steady state hot atom kinetic theory (i5.ll)-). [Pg.316]

Dynamically definite and indefinite boundaries of stability regions... [Pg.445]

We can now assert that a stability boundary is dynamically definite if upon crossing over the boundary the behavior of the representative point is uniquely defined. This situation does occur in the case where the unstable set of the equilibrium state (the periodic trajectory) contains at most one attractor at the critical parameter value. [Pg.448]

Minimum exposure times must be observed in order to reach the requisite S/N ratio. As per EN 1435 and EN 584-1, for the different ranges of utilization (energy, wall thickness), definite film elasses are prescribed. They are characterized by the minimum gradient-to-noise ratios. Based on this, one can calculate the minimum values for the S/N ratio based on the IP systems. The exposure time and the device parameter sensitivity and dynamics (latitude) must be adjusted accordingly, with an availability of an at least 12 bit system for the digitalization. [Pg.474]

It was made clear in Chapter II that the surface tension is a definite and accurately measurable property of the interface between two liquid phases. Moreover, its value is very rapidly established in pure substances of ordinary viscosity dynamic methods indicate that a normal surface tension is established within a millisecond and probably sooner [1], In this chapter it is thus appropriate to discuss the thermodynamic basis for surface tension and to develop equations for the surface tension of single- and multiple-component systems. We begin with thermodynamics and structure of single-component interfaces and expand our discussion to solutions in Sections III-4 and III-5. [Pg.48]

Definitive examples of intrinsic non-RRKM dynamics for molecules excited near their unimolecular tluesholds are rather limited. Calculations have shown that intrinsic non-RRKM dynamics becomes more pronounced at very high energies, where the RRKM lifetime becomes very short and dissociation begins to compete with IVR [119]. There is a need for establishing quantitative theories (i.e. not calculations) for identifying which molecules and energies lead to intrinsic non-RRKM dynamics. For example, at thenual... [Pg.1037]

Final state analysis is where dynamical methods of evolving states meet the concepts of stationary states. By their definition, final states are relatively long lived. Therefore experiment often selects a single stationary state or a statistical mixture of stationary states. Since END evolution includes the possibility of electronic excitations, we analyze reaction products in terms of rovibronic states. [Pg.245]

The first requirement is the definition of a low-dimensional space of reaction coordinates that still captures the essential dynamics of the processes we consider. Motions in the perpendicular null space should have irrelevant detail and equilibrate fast, preferably on a time scale that is separated from the time scale of the essential motions. Motions in the two spaces are separated much like is done in the Born-Oppenheimer approximation. The average influence of the fast motions on the essential degrees of freedom must be taken into account this concerns (i) correlations with positions expressed in a potential of mean force, (ii) correlations with velocities expressed in frictional terms, and iit) an uncorrelated remainder that can be modeled by stochastic terms. Of course, this scheme is the general idea behind the well-known Langevin and Brownian dynamics. [Pg.20]

The explicit definition of water molecules seems to be the best way to represent the bulk properties of the solvent correctly. If only a thin layer of explicitly defined solvent molecules is used (due to hmited computational resources), difficulties may rise to reproduce the bulk behavior of water, especially near the border with the vacuum. Even with the definition of a full solvent environment the results depend on the model used for this purpose. In the relative simple case of TIP3P and SPC, which are widely and successfully used, the atoms of the water molecule have fixed charges and fixed relative orientation. Even without internal motions and the charge polarization ability, TIP3P reproduces the bulk properties of water quite well. For a further discussion of other available solvent models, readers are referred to Chapter VII, Section 1.3.2 of the Handbook. Unfortunately, the more sophisticated the water models are (to reproduce the physical properties and thermodynamics of this outstanding solvent correctly), the more impractical they are for being used within molecular dynamics simulations. [Pg.366]

Lavery R and H Sklenar 1988. The Definition of Generalized Helicoidal Parameters and of A> Curvature for Irregular Nucleic Acids. Journal of Biomolecular Structure and Dynamics 5 63-91. [Pg.423]

In order to define how the nuclei move as a reaction progresses from reactants to transition structure to products, one must choose a definition of how a reaction occurs. There are two such definitions in common use. One definition is the minimum energy path (MEP), which defines a reaction coordinate in which the absolute minimum amount of energy is necessary to reach each point on the coordinate. A second definition is a dynamical description of how molecules undergo intramolecular vibrational redistribution until the vibrational motion occurs in a direction that leads to a reaction. The MEP definition is an intuitive description of the reaction steps. The dynamical description more closely describes the true behavior molecules as seen with femtosecond spectroscopy. [Pg.159]

The elastic and viscoelastic properties of materials are less familiar in chemistry than many other physical properties hence it is necessary to spend a fair amount of time describing the experiments and the observed response of the polymer. There are a large number of possible modes of deformation that might be considered We shall consider only elongation and shear. For each of these we consider the stress associated with a unit strain and the strain associated with a unit stress the former is called the modulus, the latter the compliance. Experiments can be time independent (equilibrium), time dependent (transient), or periodic (dynamic). Just to define and describe these basic combinations takes us into a fair amount of detail and affords some possibilities for confusion. Pay close attention to the definitions of terms and symbols. [Pg.133]


See other pages where Dynamic definition is mentioned: [Pg.205]    [Pg.171]    [Pg.106]    [Pg.340]    [Pg.2910]    [Pg.152]    [Pg.445]    [Pg.446]    [Pg.447]    [Pg.449]    [Pg.205]    [Pg.171]    [Pg.106]    [Pg.340]    [Pg.2910]    [Pg.152]    [Pg.445]    [Pg.446]    [Pg.447]    [Pg.449]    [Pg.361]    [Pg.53]    [Pg.79]    [Pg.883]    [Pg.887]    [Pg.914]    [Pg.914]    [Pg.1201]    [Pg.2271]    [Pg.2817]    [Pg.27]    [Pg.31]    [Pg.116]    [Pg.301]    [Pg.492]    [Pg.547]    [Pg.429]    [Pg.291]    [Pg.291]    [Pg.433]    [Pg.115]   
See also in sourсe #XX -- [ Pg.135 ]




SEARCH



Computational fluid dynamics model definition

Definition of the Model and Dynamical Matrix

Direct Dynamics definition

Dynamic Model Definition

Dynamic activity, definition

Dynamic equilibrium, definition

Dynamic flexibility definition

Dynamic loading definition

Dynamic mechanical measurements, definition

Dynamic processes definition

Dynamic range definition

Dynamic structure factors definition

Dynamic viscosity, definition

Dynamical Rules Notation and Definitions

Dynamical correlation energy definition

Dynamically definite boundaries

Molecular dynamics definition

Molecular dynamics time based definition

Polymers, dynamic, definition

Relative dynamic range definition

© 2024 chempedia.info