Variable charge many-body interatomic potentials

Shin, Yun Kyung; Shan, Tzu Ray; Liang, Tao; Noordhoek, Mark J.; Sinnott, Susan B.; Duin, Adri C. T. van; Phillpot, Simon R.

doi:10.1557/mrs.2012.95

Cited by 61 publications

(43 citation statements)

References 83 publications

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“…ρ eX is set to zero for hydrogen and is found to correlate with the atomic radii of other elements (see below). For the energy of repulsion between a pair of unlike-spin electrons, the form is similar 4) except that, in this case, the best form found for d eff is 5) where d e,i and d e,j are the cloud diameters of the two electrons. For repulsions between likespin electrons, the consequences of the fermionic requirement of wave function antisymmetry are accounted for by adding an 'exchange term' for which the best form found so far is 6) where the three adjustable parameters χ ee , τ ee1 and τ ee2 determine the amplitude, zero crossing and damping, respectively.…”

Section: (B) Interactions and Potential Formsmentioning

confidence: 90%

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Pointillist rendering of electron charge and spin density suffices to replicate trends in atomic properties

Ekesan¹,

Herzfeld²

2015

Proc. R. Soc. A.

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The monotonic and non-monotonic variations of atomic properties within and between the rows of the periodic table underlie our understanding of chemistry and accounting for these variations has been a signature strength of quantum mechanics (QM). However, the computational burden of QM motivates the development of more efficient means of describing electrons and reactivity. The recently developed LEWIS • model incorporates lessons learnt from QM into a force field that includes electrons as explicit pseudo-classical particles. Here, we extend LEWIS • across the 2p and 3p elements, and show that it is capable of reproducing both monotonic and non-monotonic variations of chemically important atomic properties in a cost-effective manner. An indicator of the strength of the construct is the ability of pairwise potentials trained on ionization energies and the order of spin configurations to predict atomic polarizabilities. In this manner, some insights of QM are uncoupled from its onerous computational burden.

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Section: (B) Interactions and Potential Formsmentioning

confidence: 90%

“…Such force fields include OPLS [1], CHARMM [2] and AMBER [3]. For reactive force fields, in which bonds can be made and broken [4][5][6], electrons are also implicit in the 2. LEWIS • (a) Particles LEWIS • unpacks atoms into fully charged valence electrons (e) and atomic kernels (X) that include the core electrons.…”

Section: Introductionmentioning

confidence: 99%

Pointillist rendering of electron charge and spin density suffices to replicate trends in atomic properties

Ekesan¹,

Herzfeld²

2015

Proc. R. Soc. A.

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“…On the purely empirical side, restricting our discussion to the more transferable methods, Baskes and co-workers have developed the embedded atom method (EAM 65,66 ), which-opposite to ReaxFF-was mainly formulated for metals, yet has since been modified (MEAM 67 ) to treat oxides, hydrides and hydrocarbons. Furthermore, the bondorder concept, as initiated by Abell, 68 Tersoff, 69,70 and Brenner, 71 was further developed into the AIREBO method 72 by Stuart, Tutein and Harrison, as well as into the highly transferable COMB method [73][74][75][76][77] by Sinnott, Philpott, and co-workers. We refer readers to recent reviews for more in-depth comparisons of empirical reactive methods, 73,74 and of simulation methods for large-scale molecular dynamics on reactive systems.…”

Section: Current Reaxff Methodologymentioning

confidence: 99%

“…Furthermore, the bondorder concept, as initiated by Abell, 68 Tersoff, 69,70 and Brenner, 71 was further developed into the AIREBO method 72 by Stuart, Tutein and Harrison, as well as into the highly transferable COMB method [73][74][75][76][77] by Sinnott, Philpott, and co-workers. We refer readers to recent reviews for more in-depth comparisons of empirical reactive methods, 73,74 and of simulation methods for large-scale molecular dynamics on reactive systems. 78 In general, empirical methods tend to be faster and scale better than QM-based approaches, 79 although relatively few head-tohead comparisons have appeared in the literature so far.…”

Section: Current Reaxff Methodologymentioning

confidence: 99%

The ReaxFF reactive force-field: development, applications and future directions

et al. 2016

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The reactive force-field (ReaxFF) interatomic potential is a powerful computational tool for exploring, developing and optimizing material properties. Methods based on the principles of quantum mechanics (QM), while offering valuable theoretical guidance at the electronic level, are often too computationally intense for simulations that consider the full dynamic evolution of a system. Alternatively, empirical interatomic potentials that are based on classical principles require significantly fewer computational resources, which enables simulations to better describe dynamic processes over longer timeframes and on larger scales. Such methods, however, typically require a predefined connectivity between atoms, precluding simulations that involve reactive events. The ReaxFF method was developed to help bridge this gap. Approaching the gap from the classical side, ReaxFF casts the empirical interatomic potential within a bond-order formalism, thus implicitly describing chemical bonding without expensive QM calculations. This article provides an overview of the development, application, and future directions of the ReaxFF method. INTRODUCTIONAtomistic-scale computational techniques provide a powerful means for exploring, developing and optimizing promising properties of novel materials. Simulation methods based on quantum mechanics (QM) have grown in popularity over recent decades due to the development of user-friendly software packages making QM level calculations widely accessible. Such availability has proved particularly relevant to material design, where QM frequently serves as a theoretical guide and screening tool. Unfortunately, the computational cost inherent to QM level calculations severely limits simulation scales. This limitation often excludes QM methods from considering the dynamic evolution of a system, thus hampering our theoretical understanding of key factors affecting the overall behaviour of a material. To alleviate this issue, QM structure and energy data are used to train empirical force fields that require significantly fewer computational resources, thereby enabling simulations to better describe dynamic processes. Such empirical methods, including reactive force-field (ReaxFF), 1 trade accuracy for lower computational expense, making it possible to reach simulation scales that are orders of magnitude beyond what is tractable for QM.Atomistic force-field methods utilise empirically determined interatomic potentials to calculate system energy as a function of atomic positions. Classical approximations are well suited for nonreactive interactions, such as angle-strain represented by harmonic potentials, dispersion represented by van der Waals potentials and Coulombic interactions represented by various polarisation schemes. However, such descriptions are inadequate for modelling changes in atom connectivity (i.e., for modelling chemical reactions as bonds break and form). This motivates the

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“…ReaxFF is an advanced bond-order based, variable charge force field that enables large-scale simulations of chemically reactive systems. Full details of ReaxFF can be found elsewhere [17][18][19]. The particular ReaxFF parameterization used in this work was developed for nitramines [20] and was extended to triacetone triperoxide (TATP) [21] and nitromethane [22].…”

Section: Computational Detailsmentioning

confidence: 99%

Shock-induced hotspot formation and chemical reaction initiation in PETN containing a spherical void

Shan

Thompson

2014

J. Phys.: Conf. Ser.

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Abstract. We present results of reactive molecular dynamics simulations of hotspot formation and chemical reaction initiation in shock-induced compression of pentaerythritol tetranitrate (PETN) with the ReaxFF reactive force field. A supported shockwave is driven through a PETN crystal containing a 20 nm spherical void at a sub-threshold impact velocity of 2 km/s. Formation of a hotspot due to shock-induced void collapse is observed. During void collapse, NO2 is the dominant species ejected from the upstream void surface. Once the ejecta collide with the downstream void surface and the hotspot develops, formation of final products such as N2 and H2O is observed. The simulation provides a detailed picture of how void collapse and hotspot formation leads to initiation at sub-threshold impact velocities.

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Variable charge many-body interatomic potentials

Abstract: Abstract

Cited by 61 publications

References 83 publications

Pointillist rendering of electron charge and spin density suffices to replicate trends in atomic properties

Pointillist rendering of electron charge and spin density suffices to replicate trends in atomic properties

The ReaxFF reactive force-field: development, applications and future directions

Shock-induced hotspot formation and chemical reaction initiation in PETN containing a spherical void

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