COMB potential, parameterization

Because the electrostatic energy terms for an uncharged pure system (such as a bulk structure) is zero, the energy contribution of COMB for such a system is from the short-range interactions [eqn (7.18)] and the formalism is reduced to the Tersoff type of potential. This case is straightforward for the parameterization of the COMB potential, which only fits parameters in the pairwise term and bond-order terms, as shown in Table 7.2. The van der Waals interaction will be considered for hydrocarbon systems. 

Lastly, the COMB poetical is fit to the binary system with multiple phases. Similar to the parameterization process for a pure system, the potential starts with fitting the pairwise terms to the phase orders and charge of a variety of binary systems, which is followed by fitting the parameters in many-body terms to the properties of the binary system. The parameters involved in the binary system are listed in Table 7.4. 

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