Atomistic Theory

Pecchia A, Di Carlo A (2004) Atomistic theory of transport in organic and inorganic nanostructures. Rep Prog Phys 67(8) 1497-1561... 

According to E. Stroker [1], it was not the Democritean atomistic theory of matter which was the precursor of the modem Daltonian atomic theory, as generally accepted, but the Aristotelian concept of minima naturalia, developed in the Middle Age. 

Atomistic theory of nucleation — The theory applies to very small clusters, the size n of which is a discrete variable and the process of nucleus formation must be described by means of atomistic considerations. Thus, the thermodynamic barrier AG ( ) that has to be overcome in order to form an n-atomic nucleus of the new phase is given by the general formula [i-v]... 

Nucleation — Atomistic theory of nucleation — Figure 1. Dependence of the nucleation work AG (ft) on the cluster size n (a) and dependence of the critical nucleus size nc on the supersaturation Ap (b) according to the atomistic nucleation theory (a schematic representation)... 

Dipole scattering does not require an atomistic theory. A phenomenological theory suffices, which includes a response function dependent on dielectric constants. The cross-section for dipole scattering based on these assumptions is given in Eqs, 3.7 and 3.9 of Ibach and Mills./61/ These formulae include plane-wave reflection coefficients from the surface, which are solutions of the standard LEED problem. Since dipole scattering involves essentially only forward scattering, it is not necessary in practice to adopt the spherical-wave picture of our step 2 (cf. section 3.4.3), the plane-wave approach is adequate in this situation. 

Explain diamagnetism, paramagnetism, ferromagnetism, and antiferromagnetism using a) a phenomenological description of macroscopic behavior and b) microscopic (atomistic) theory. 

An alternative approach to the problem is provided by the atomistic lattice-energy calculations discussed in Section 2, p. 108. In addition to the obvious advantages of atomistic theories, such calculations also require no assumptions as to the nature of the shear-plane interactions. Thus electrostatic terms, which may play an appreciable role in shear-plane systems are automatically included in such theories. Ordered shear-plane compounds, e.g. the Ti 02 -i, series can be described in terms of large unit cells. If the lattice energies of these structures are calculated as described in E. Iguchi and R. J. D. Tilley, Phil. Trans., 1977, 286, 55. 

Under the specific conditions of electrochemical metal deposition, the critically sized clusters of the new phase have been found to consist of only a few atoms, where classical thermodynamic bulk quantities cannot be applied. Therefore, the original kinetic theory of Becker and Doering was further developed to an atomistic theory of nucleation. 

The atomistic theory becomes of additional significance for the transition from 2D Me phase formation in the UPD range to 3D Me phase formation in the OPD range. Experimental results obtained using modern in situ techniques with lateral atomic resolution showed that the transition phenomena can only be interpreted on the basis of atomistic approaches. The UPD surface modification turns out to be a more general phenomenon affecting not only the nucleation processes but also the growth mode and epitaxy of 3D metal phases. 

Matter in general is made possible by the inseparable bond between attraction and repulsion. Because the proportion of these forces may vary, the possibility of an infinite variety of chemical substances is given. Hence, the first causes are not mechanical (as in atomist theories), but physico-dynamic.69 The interaction between the omnipresent ether and the two originary forces creates the specific differences between types of matter. Each chemical substance is characterized by a quantity of ether and three forces [universal attractive force, proper repulsive force, and proper attractive force (chemical cohesion)]. Hence, the ether is the ultimate origin of the variety of substances (together with the two moving forces). 

Classical nucleation theory may be not well suited to describe the nucleation kinetics of diamond in CVD, since the critical nucleus size under the typical CVD conditions may be on the order of a few atoms. The surface energy contribution may cause a reverse effect on the phase stability and the GFobs free-energy of the formation of a critical nucleus may be negative, a case referred to as nonclassical nucleation. In such a case, atomistic theory should be employed as the starting point of theoretical analyses. 

Describing tune type is perhaps the most difficult issue in prosody. Tune schemes can be broadly divided into those which classify tunes using dynamie features (rises and falls) and those which use static features (tones). Theories also vary in the size of the units they use. Global descriptions make use of a few basic patterns that cover the entire phrase, atomistic theories make use of smaller units that combine together to form larger patterns. Jones [242] is at the global end of the seale, the British school [333], [193] uses sub-phrase units (see Section 9.3.1, while the AM school [352], [351] and the Dutch school [446] use units whieh are smaller still (Seetions 9.3.2, 9.3.3. 

Nernst applied the atomistic theory of electricity to chemistry, calling the unit charges positive and negative electrons, and , which combine with atoms or radicals to form ions. He had the idea that and 0 combine to form a neutral particle constituting the ether of space (Ampere had suggested this). In his last years Nernst devoted much time to cosmological speculations. 

Stoyanov [6] reexamined Walton s atomistic theory of heterogeneous nucleation and derived the nucleation rate avoiding... 

According to Eq. (45), the atomistic theory predicts a linear dependence of the nucleation rate with overpotential for constant size of the critical nucleus, as shown in Fig. 7. Also, in accordance with Eq. (45), the value of the slope doubles for mercury deposition from Hg(II) as compared with deposition from Hg(I). 

Three-dimensional nucleation is still in a very early stage of development. Significant progress has, however, been evidently made by the introduction of the atomistic theory, but we are obviously still far from an adequate understanding of the processes of nucleation, cluster orientation, grain growth interaction, dendrite formation, and properties of bulk deposits. 

Milchev, A., Stoyanov, S. and Kaischew, R. (1974) Atomistic theory of electrolytic nucleation I. Thin Solid Films, 22, 255-265. 

Stoyanov, S. (1973) On the atomistic theory of nucleation rate. Thin Solid Films, 18, 91—98. 

Leucippus (fl. 500 BCE) Greek philosopher who is said to have originated the atomistic theory that was taken up by Democritus and the poet Lucretius. 

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