The Channeling of Energetic Atoms in Crystal Lattices

Robinson, M. T.; Oen, O.S.

doi:10.1063/1.1753757

Cited by 243 publications

(45 citation statements)

References 10 publications

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“…In the latter case, a search for collision partners must be made within the lattice surrounding the cascade ion path. Early simulations using the BCA in ordered lattices [106,107,108] provided the first means of exploring the anomalies discovered in experimental range distributions in polycrystalline targets [109] and attributed to ion channelling.…”

Section: Binary Collision Modelsmentioning

confidence: 99%

The treatment of electronic excitations in atomistic models of radiation damage in metals

Race¹,

Mason²,

Finnis³

et al. 2010

Rep. Prog. Phys.

135

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Abstract. Atomistic simulations are a primary means of understanding the damage done to metallic materials by high energy particulate radiation. In many situations the electrons in a target material are known to exert a strong influence on the rate and type of damage. The dynamic exchange of energy between electrons and ions can act to damp the ionic motion, to inhibit the production of defects or to quench in damage, depending on the situation. Finding ways to incorporate these electronic effects into atomistic simulations of radiation damage is a topic of current major interest, driven by materials science challenges in diverse areas such as energy production and device manufacture.In this review, we discuss the range of approaches that have been used to tackle these challenges. We compare augmented classical models of various kinds and consider recent work applying semi-classical techniques to allow the explicit incorporation of quantum mechanical electrons within atomistic simulations of radiation damage. We also outline the body of theoretical work on stopping power and electron-phonon coupling used to inform efforts to incorporate electronic effects in atomistic simulations and to evaluate their performance.

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Section: Binary Collision Modelsmentioning

confidence: 99%

The treatment of electronic excitations in atomistic models of radiation damage in metals

Race¹,

Mason²,

Finnis³

et al. 2010

Rep. Prog. Phys.

135

View full text Add to dashboard Cite

show abstract

“…Channeling was discovered in the early 1960s by cornputer simulatioris of ion motion in crystals [1,2]. Large penetration lengths were obtained for ions inciderit along crystallographic directions of low indexes.…”

Section: Introductionmentioning

confidence: 99%

Channeling process in a bent crystal

1996

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We have investigated the channeling process of charged particles in a bent crystal. Invoking simple assumptions we derive a criterion, which determines whether channeling occurs or not. We obtain the same criterion using the Dirac equation. It is shown that the centrifugal force acting on the particle in the berit crystal significantly alters the effective transverse potential. The cases of axial and planar channeling are considered. The channeling probability and the dechanneling probability due to tunneling of the particle under the barrier in the effective transverse potential are estimated. These probabilities depend on the specific scaling parameter characterizing the process. Using the quasiclassical theory of synchrotron radiation we have calculated the ~ontribut~ion to the radiation spectrum, which arises due to the curvature of the channel. This contribution beconies significant for TeV electrons or positrons. Some practical consequences of our results are briefly discussed.

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“…Then we can show (see appendix A.5) 85) exact to second order in δρ(r) and (see appendix A.6) that (4.86) again to second order in δρ(r). Our new functional thus becomes, to second order…”

Section: The Harris-foulkes Functionalmentioning

confidence: 99%

“…it was early BCA simulations in crystalline lattices [84][85][86] that provided a means of exploring anomalies in experimental range data in crystalline targets [87] and confirmed the role of ion channelling. What is more, the relatively low computational cost of BCA simulations (because the target material is generated 'on the fly') has ensured that they remain in common use up to the present day.…”

Section: The Binary Collision Approximationmentioning

confidence: 99%

The Modelling of Radiation Damage in Metals Using Ehrenfest Dynamics

Race

2011

Springer Theses

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In this thesis we use a time-dependent tight-binding model metal evolving under semiclassical Ehrenfest dynamics to explore the effects of electron-ion energy exchange on radiation damage phenomena. By incorporating an explicit model of quantum mechanical electrons coupled to a set of classical ions, our model correctly reproduces the interaction of excited ions with cooler electrons and captures phenomena absent in classical molecular dynamics simulations and in much-used analytical models.With our simple model we have been able to simulate large numbers of radiation damage cascades. We have directly explored the electronic excitations stimulated in such cascades and have found them to be well characterized by an elevated electronic temperature. We have also analysed the effect of these excitations in weakening the bonding interactions in our model metal, and the effect of these weakened interactions on the evolution of replacement collision sequences.By separating out components of the Hellmann-Feynman forces exerted by the electrons on the ions, we have identified the non-adiabatic force, resulting from the finite response time of the electrons to ionic motion and responsible for the accumulating electronic excitations. Based on simplifying physical arguments we have derived a temporallyand spatially-local expression for this force suitable for incorporation within a classical MD code at very low computational cost. Data from our simulations show that our new expression for the non-adiabatic force captures much of the microscopic detail of the direction and magnitude of the force. We find that it significantly outperforms commonly used viscous damping models of ion-electron energy transfer.At higher energies, our simulations of ion channelling reveal a new resonant enhancement of the electronic charge on the channelling ion and corresponding effects on the stopping force. We explain these phenomena with reference to the detailed atomic and electronic structure of our model.

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The Channeling of Energetic Atoms in Crystal Lattices

Cited by 243 publications

References 10 publications

The treatment of electronic excitations in atomistic models of radiation damage in metals

The treatment of electronic excitations in atomistic models of radiation damage in metals

Channeling process in a bent crystal

The Modelling of Radiation Damage in Metals Using Ehrenfest Dynamics

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