Embedded atom method potential

Lutsko J F ef a/1989 Molecular-dynamic study of lattice-defect-nucleated melting in metals using an embedded-atom-method potential Phys. Rev. B 40 2841... 

Mitev, P., Evangelakis, G.A., and Efihimios Kaxiras (2005) Embedded atom method potentials employing a faithful density representation. Modelling and Simulation in Mater. Science and Engineering, 14,721-731. 

Y. Le Bouar and F. Soisson, Kinetics pathway from embedded-atom-method potential Influence of the activation barriers, Phys. Rev. B, vol. 65, p. 0914103, 2002. 

As a first basic example, we consider the diffusion of a Cu adatom on a solid Cu (001) surface, as simulated by tfMC [47]. The Cu-Cu interaction was described by the standard embedded atom method potential. The diffusion coefficient was determined directly from the calculated trajectories, and the rate constant was calculated from the Arrhenius equation. The tfMC simulations were carried out using A = 0.10 A, corresponding to an average MC time step between 7.8 and 10 fs, in the temperature range 550-900 K, and compared with both MD simulations as well as with the literature. The dynamics of the adatom diffusion process as determined from the tfMC algorithm are shown in Fig. 2. It was found that tfMC correctiy reproduces the different diffusion mechanisms as observed in the MD simulations. Also, the activation barrier as determined from... 

A full-scale treatment of crystal growth, however, requires methods adapted for larger scales on top of these quantum-mechanical methods, such as effective potential methods like the embedded atom method (EAM) [11] or Stillinger-Weber potentials [10] with three-body forces necessary. The potentials are obtained from quantum mechanical calculations and then used in Monte Carlo or molecular dynamics methods, to be discussed below. 

We have used the embedded-atom method (EAM) to develop interatomic potentials suitable for the simulation of iron-nickel alloys. In this method the total energy of the alloys can be written as... 

The main handicap of MD is the knowledge of the function [/( ). There are some systems where reliable approximations to the true (7( r, ) are available. This is, for example, the case of ionic oxides. (7( rJ) is in such a case made of coulombic (pairwise) interactions and short-range terms. A second example is a closed-shell molecular system. In this case the interaction potentials are separated into intraatomic and interatomic parts. A third type of physical system for which suitable approaches to [/( r, ) exist are the transition metals and their alloys. To this class of models belong the glue model and the embedded atom method. Systems where chemical bonds of molecules are broken or created are much more difficult to describe, since the only way to get a proper description of a reaction all the way between reactant and products would be to solve the quantum-mechanical problem at each step of the reaction. 

While the embedded atom method has been formally derived by Daw and Baskes the functions used in computer simulations are t3pically empirically determined. The description presented here will therefore treat this approach as an empirical method. The first step in determining the potential is to define a local electron density at each atomic site in the solid. A simple sum of atomic electron densities has proven to be adequate, and so in most cases a sum of free atom densities is used . The second step is to determine an embedding... 

Now that the top-down internal state variable theory was established, the bottom-up simulations and experiments were required. At the atomic scale (nanometers), simulations were performed using Modified Embedded Atom Method, (MEAM) Baskes [176], potentials based upon interfacial atomistics of Baskes et al. [177] to determine the conditions when silicon fracture would occur versus silicon-interface debonding [156]. Atomistic simulations showed that a material with a pristine interface would incur interface debonding before silicon fracture. However, if a sufficient number of defects were present within the silicon, it would fracture before the interface would debond. Microstructural analysis of larger scale interrupted strain tests under tension revealed that both silicon fracture and debonding of the silicon-aluminum interface in the eutectic region would occur [290, 291]. 

Y. Li et al Embedded-atom-method tantalum potential developed by the force-matching method. Phyl. Rev. B Cond. Mattr Matls. Phys 67, 125101 (2003)... 

M.I. Baskes Application of the embedded-atom method to covalent materials a semiempi-rical potential for silicon. Physl. Rev. Lett. 59, 2666-2669 (1987)... 

B. Jelinek et al Modified embedded-atom method interatomic potentials for the Mg-Al alloy system. Physl. Rev. B 75, 054106 (2007)... 

Although a valence-type force field of the type illustrated by Eq. [1] is most suitable for modeling molecular systems, the electronegativity equalization approach to treating polarization can be coupled equally well to other types of potentials. Streitz and Mintmire used an EE-based model in conjunction with an embedded atom method (EAM) potential to treat polarization effects in bulk metals and oxides. The resulting ES + EAM model has been parameterized for aluminum and titanium oxides, and has been used to study both charge-transfer effects and reactivity at interfaces. 

Metals can also be simulated using empirical multibody potential functions developed from quantum-mechanical results. One procedure that has been successful is the embedded-atom method [30,31], which focuses on the quantum-mechanically-derived energy required to introduce an atom into the host metal. This energy is considered to be a function only of the electron density at the point of insertion, and is written as a sum of two terms A... 

Ni v clusters have been the subject of very many theoretical studies (see, e.g., 33 and references therein). Wetzel and DePristo80 studied Ni clusters for 24 < N < 55 using the so-called effective-medium potential which is similar to the embedded-atom methods described above. They used a molecular-dynamics approach in optimizing the structure, and identified particularly stable structures through the total-energy difference between the energetically two lowest isomers for a given N, i.e., AUE(N) of Eq. (51). 

When angular-dependent interactions contribute significantly to the bonding, pair potentials like those described above are not sufficient and three-body or higher order terms must be included in the potential energy. That is the case of covalently bonded systems like silicon or transition metals. For the case of silicon two interatomic potentials are widely used the one developed by StiUinger and Weber [20] and the one developed by Tersoff [21]. Other empirical potentials have been developed to include the angular dependence such as the modified embedded atom method (MEAM) [22]. 

A fundamental requirement on all of the computational studies on metal surface dynamics is fhe need fo perform simulafions with realistic potentials and in a feasible amounf of fime. To this end, the temperature-accelerated dynamics method [14,74,75] has arisen as a possible approach for reaching the latter limit. With the exception of quanfum simulations, most classical simulations are based on semiempirical potentials derived either from the embedded atom method or effective medium theory [76-78]. However a recent potential energy surface for hydrogen on Cu(l 10) based on density functional theory calculations produced qualitatively different results from those of the embedded atom method including predictions of differenf preferred binding sites [79]. 

For larger Au NPs many theoretical calculations have been made using empirical interatomic potentials. A number of different models have been developed to represent the many-body character of bonding in metals, for example, Finnis-Sinclair, Gupta, and glue models. Here, we discuss the embedded atom method (EAM), which has many similarities with the models mentioned above but can be considered as more... 

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