The reactive empirical bond-order (REBO) model is a function for calculating the

potential energy In physics, potential energy is the energy held by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors. Common types of potential energy include the gravitational potentia ...

covalent bonds A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atom ...

and the interatomic force. In this model, the total

of system is a sum of nearest-neighbour pair interactions which depend not only on the distance between atoms but also on their local atomic environment. A parametrized

bond order In chemistry, bond order, as introduced by Linus Pauling, is defined as the difference between the number of bonds and anti-bonds. The bond order itself is the number of electron pairs ( covalent bonds) between two atoms. For example, in diat ...

function was used to describe chemical pair bonded interactions. The early formulation and parametrization of REBO for carbon systems was done by Tersoff in 1988, based on works of Abell. The Tersoff's model could describe single, double and triple bond energies in carbon structures such as in hydrocarbons and diamonds. A significant step was taken by Brenner in 1990. He extended Tersoff's potential function to radical and conjugated hydrocarbon bonds by introducing two additional terms into the bond order function. Compared to classical first-principle and

semi-empirical Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences and ...

approaches, the REBO model is less time-consuming, since only the 1st- and 2nd-nearest-neighbour interactions were considered. This advantage of computational efficiency is especially helpful for large-scale atomic simulations (from 1000 to 1000000 atoms). In recent years, the REBO model has been widely used in the studies concerning mechanical and thermal properties of

carbon nanotubes A scanning tunneling microscopy image of a single-walled carbon nanotube Rotating single-walled zigzag carbon nanotube A carbon nanotube (CNT) is a tube made of carbon with diameters typically measured in nanometers. ''Single-wall carbon nan ...

. Despite numerous successful applications of the first-generation REBO potential function, its several drawbacks have been reported. e.g. its form is too restrictive to simultaneously fit equilibrium distances, energies, and force constants for all types of C-C bonds, the possibility of modeling processes involving energetic atomic

collisions In physics, a collision is any event in which two or more bodies exert forces on each other in a relatively short time. Although the most common use of the word ''collision'' refers to incidents in which two or more objects collide with great fo ...

is limited because both Morse-type terms go to finite values when the atomic distance decreases, and the neglect of a separate pi bond contribution leads to problems with the overbinding of radicals and a poor treatment of conjugacy. To overcome these drawbacks, an extension of Brenner's potential was proposed by Stuart et al. It is called the adaptive intermolecular reactive bond order (AIREBO) potential, in which both the repulsive and attractive pair interaction functions in REBO function are modified to fit bond properties, and the long-range atomic interactions and single bond torsional interactions are included. The AIREBO model has been used in recent studies using numerical

simulations A simulation is the imitation of the operation of a real-world process or system over time. Simulations require the use of Conceptual model, models; the model represents the key characteristics or behaviors of the selected system or proc ...

.{{cite journal , last1=Nikitin , first1=A. , last2=Ogasawara , first2=H. , last3=Mann , first3=D. , last4=Denecke , first4=R. , last5=Zhang , first5=Z. , last6=Dai , first6=H. , last7=Cho , first7=K. , last8=Nilsson , first8=A. , title=Hydrogenation of Single-Walled Carbon Nanotubes , journal=Physical Review Letters , publisher=American Physical Society , volume=95 , issue=22 , date=23 November 2005 , issn=0031-9007 , doi=10.1103/physrevlett.95.225507 , pmid=16384236 , page=225507, arxiv=cond-mat/0510399 , s2cid=14520468

References

Chemical physics Chemical bonding