A new interatomic potential function for helium

Beck, D. E.

doi:10.1080/00268976800100381

Cited by 332 publications

(97 citation statements)

References 21 publications

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“…In addition we include He-He interactions by summing over the corresponding V He-He (R) potentials between neighboring helium atoms using the semiempirical potential given by Beck [14]. The distance R between two neighboring helium atoms is a function of the cesium-helium separation r and the number n of helium atoms: R = |r i − r i+1 | = 2r sin(π/n).…”

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confidence: 99%

Discovery of Dumbbell-ShapedCs*HenExciplexes in Solid

et al. 2005

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We have observed several new spectral features in the fluorescence of cesium atoms implanted in the hcp phase of solid helium following laser excitation to the 6 2 P states. Based on calculations of the emission spectra using semiempirical Cs-He pair potentials the newly discovered lines can be assigned to the decay of specific Cs * Hen exciplexes: an apple-shaped Cs(AΠ 3/2 )He2 and a dumbbellshaped Cs(AΠ 1/2 )Hen exciplex with a well defined number n of bound helium atoms. While the former has been observed in other enviroments, it was commonly believed that exciplexes with n > 2 might not exist. The calculations suggest Cs(AΠ 1/2 )He6 to be the most probable candidate for that exciplex, in which the helium atoms are arranged on a ring around the waist of the dumbbell shaped electronic density distribution of the cesium atom.PACS numbers: 76.70. Hb,32.80.Wr,32.30.Dx,32.60.+i Alkali atoms and helium atoms in their ground states strongly repel each other by virtue of the Pauli principle. However, an alkali atom excited to one of its P states can exert an attractive potential on a helium atom that can lead to bound states, known as exciplexes. The formation of alkali-helium exciplexes was considered for the first time by Dupont-Roc [1] and Karnorsky et al. [2] as an explanation for the observed quenching of atomic fluorescence from light alkali atoms (Na, Li) embedded in liquid or solid 4 He. In the meantime such molecules have been observed in different environments, such as liquid helium and cold helium gas [3,4] , as well as on the surface of helium nanodroplets [5,6,7,8] . Here we present the first observations of such exciplexes in a solid helium matrix.In earlier experiments [2] we have studied the excitation and fluorescence spectra of atomic cesium implanted into the bcc and hcp phases of solid helium. It was found that the excitation at the D 1 transition (6S 1/2 -6P 1/2 ) results in atomic fluorescence at the same transition, blue shifted (with respect to the free Cs atom) by the interaction with the helium matrix. At the same time, excitation on the D 2 transition (6S 1/2 -6P 3/2 ) produced merely a weak fluorescence on the D 1 emission line, which indicates that the 6P 3/2 atoms are partly quenched into the 6P 1/2 state, while the main relaxation channel remained unknown. Recently, the extension of the spectral range of our detection system allowed us to discover several new emission lines, red shifted with respect to the atomic fluorescence line. We attribute those lines to the formation and decay of Cs * He n molecules.

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Discovery of Dumbbell-ShapedCs*HenExciplexes in Solid

et al. 2005

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“…The system of self-consistent equations is solved for the (exp, m) Buckingham, the (n, m) Lennard-Jones and the (exp, exp) Morse renormalized potentials. The results obtained are compared with experimental and other theoretical data [6][7][8]18] calculated in terms of the interatomic potential curves of Beck [19], Murrell and Shaw [20] and the (12,6) Lennard-Jones.…”

Section: Introductionmentioning

confidence: 93%

“…A more realistic potential has been constructed by Beck [19]. In this interatomic function the longrange attraction has the correct theoretical dependence on separation and the short-range repulsive part of the potential was fitted to the experimentally determined potential energy function.…”

Section: Interatomic Potential Function For Solid Heliummentioning

confidence: 99%

Dynamic and thermodynamic properties of solid helium in the reduced all‐neighbours approximation of the self‐consistent phonon theory

Malinowska-Adamska

Słoma

Tomaszewski

2003

Physica Status Solidi (b)

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The results of studies of physical properties of solid helium obtained with the help of the reduced allneighbours approximation of the self-consistent phonon theory are presented. The results of calculation of the temperature and pressure variations of the quantities describing the dynamics and thermodynamics of solid He-3 and He-4 obtained in terms of the (exp, m) Buckingham, the (n, m) Lennard-Jones and the (exp, exp) Morse renormalized potentials are given and compared with experimental and other theoretical data.Работа содержит результаты исследования физических свойств кристаллов гелия в приближении всех соседей второго порядка самосогласованной теории фононного поля. Численные расчёты зависимостей динамических и термодинамических свойств кристаллов He-3 и He-4 от температуры и внешнего давления, полученные с помощью межатомных самосогласованных потенциалов: (exp, m) Букингама, (n, m) Леннарда-Джонса и (exp, exp) Морзе показали правильную физическую зависимость и хорошо совпадают с експериментальными данными.

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“…10 The Ackland et al 11 embedded atom potential was used for Fe-Fe interactions. The Juslin and Nordlund pair potential 12 was used for Fe-He and the Beck 13 pair potential for He-He. The Beck He-He potential was splined to the Ziegler-Biersack-Littmark (ZBL) 14 universal potential at short range.…”

Section: Methodsmentioning

confidence: 99%

Molecular dynamics and object kinetic Monte Carlo study of radiation-induced motion of voids and He bubbles in bcc iron

Galloway

Ackland

2013

Phys. Rev. B

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We show that voids adjacent to radiation damage cascades can be moved in their entirety by several lattice spacings. This is done using molecular dynamics cascade simulations in iron at energies of 1-5 keV. An equation describing this process is added to an an object kinetic Monte Carlo (OKMC) code to allow study of the mechanism at longer time scales. The mechanism produces an enhancement of void diffusion by two orders of magnitude from 1 × 10 −22 cm 2 /s to 3 × 10 −20 cm 2 /s. Repeating the study on He bubbles shows that the movement is damped by the presence of helium in the void.

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A new interatomic potential function for helium

Cited by 332 publications

References 21 publications

Discovery of Dumbbell-ShapedCs*HenExciplexes in Solid

Discovery of Dumbbell-ShapedCs*HenExciplexes in Solid

Dynamic and thermodynamic properties of solid helium in the reduced all‐neighbours approximation of the self‐consistent phonon theory

Molecular dynamics and object kinetic Monte Carlo study of radiation-induced motion of voids and He bubbles in bcc iron

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