Full-correlation single-particle positron potentials for a positron and positronium interacting with atoms

Zubiaga, A.; Tuomisto, Filip; Puska, Martti J.

doi:10.1103/physreva.89.052707

Cited by 14 publications

(25 citation statements)

References 42 publications

(66 reference statements)

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“…Zubiaga et al . [27,18,36] have used ECG-SVM and external confining potentials to study unbound positronic systems including e + H, e + He and specially HePs. By choosing a large enough confinement radius, the wavefunction could be calculated accurately in the interaction region.…”

Section: Many-body Calculations For the Psmentioning

confidence: 99%

Modeling positronium beyond the single particle approximation

Zubiaga

Ervasti²,

Makkonen

et al. 2016

J. Phys. B: At. Mol. Opt. Phys.

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Understanding the properties of the positronium atom in matter is of interest for the interpretation of positron annihilation experiments. This technique has a unique capability for the investigation of nanometer sized voids and pores soft molecular materials (polymers, liquids or biostructures) and porous materials. However, detailed interpretations of the experimental data rely on modeling of the annihilation properties of positronium in the host material. New applications of the technique are being developed but the computational models still are based on single particle approaches and there is no way to address the influence of the electronic properties of the host material. In this work we discuss new directions of research.

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Section: Many-body Calculations For the Psmentioning

confidence: 99%

Modeling positronium beyond the single particle approximation

Zubiaga

Ervasti²,

Makkonen

et al. 2016

J. Phys. B: At. Mol. Opt. Phys.

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“…Instead it has a shallow attractive well for separations from the nucleus of 1.3 a.u. [12]. We consider now low energy Ps scattering off He in order to study the adequacy of V Ps eff to model Ps states.…”

Section: Single-particle Interaction Potentialsmentioning

confidence: 99%

Pick-Off Annihilation of Positronium in Matter Using Full Correlation Single Particle Potentials: Solid He

2015

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We investigate the modeling of positronium (Ps) states and their pick-off annihilation trapped at open volumes pockets in condensed molecular matter. Our starting point is the interacting many-body system of Ps and a He atom because it is the smallest entity that can mimic the energy gap between the highest occupied and lowest unoccupied molecular orbitals of molecules and yet the the many-body structure of the HePs system can be calculated accurately enough. The exactdiagonalization solution of the HePs system enables us to construct a pair-wise full-correlation single-particle potential for the Ps-He interaction and the total potential in solids is obtained as a superposition of the pair-wise potentials. We study in detail Ps states and their pick-off annihilation rates in voids inside solid He and analyse experimental results for Ps-induced voids in liquid He obtaining the radii of the voids. More importantly, we generalize our conclusions by testing the validity of the Tao-Eldrup model, widely used to analyse ortho-Ps annihilation measurements for voids in molecular matter, against our theoretical results for the solid He. Moreover, we discuss the influence of the partial charges of polar molecules and the strength of the van der Waals interaction on the pick-off annihilation rate.

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“…The formally exact expression for the TD electron-positron correlation functional is then derived by extending the TDDFT action principle [29] to a MC system. Furthermore, we introduce the adiabatic local density approximation (ALDA) to the TD electron-positron correlation, and adopt the ground-state electron-positron correlation energy functional within the LDA [15]. Finally, the TDM-CDFT method is applied to the dynamics of a positronic lithium hydride (e + -LiH) molecule under a laser field and elucidate the significant role of TD electron-positron correlation in their coupled dynamics.…”

mentioning

confidence: 99%

“…Specifically, the LDA [33] is used for E − xc . For E −+ c , we also use the LDA parameterized by Puska et al, which has been reported to be suitable for the ground state of positronic atoms [15].…”

mentioning

confidence: 99%

“…The bond length is set to the experimental value of 1.60Å [35]. One positron is then added to the LiH molecule, and the ground-state electron and positron densities are determined by the selfconsistent 2C-DFT calculation [2,11] using LDA both for E − xc [33] and E −+ c [15] and the plane wave basis set with norm conserving pseudopotentials [36] (cut off energy of 816 eV).…”

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confidence: 99%

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Time-Dependent Multicomponent Density Functional Theory for Coupled Electron-Positron Dynamics

2018

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Electron-positron interactions have been utilized in various fields of science. Here we develop time-dependent multi-component density functional theory to study the coupled electron-positron dynamics from first principles. We prove that there are coupled time-dependent single-particle equations that can provide the electron and positron density dynamics, and derive the formally exact expression for their effective potentials. Introducing the adiabatic local density approximation to time-dependent electron-positron correlation, we apply the theory to the dynamics of a positronic lithium hydride molecule under a laser field. We demonstrate the significance of electron-positron dynamical correlation by revealing the complex positron detachment mechanism and the suppression of electronic resonant excitation by the screening effect of the positron.When a low-energy positron beam is directed to a material, the incident positron diffuses inside the bulk and is finally annihilated with atomic electrons and γ rays are emitted [1]. Analysis of these γ rays provides various information related with the surface structures, lattice defects, and electronic structures of the material [1][2][3]. The analysis of positron-annihilation γ rays has been utilized in many applications, such as positron annihilation spectroscopy [4] and positron emission tomography [5]. The positron-material interaction plays a key role in these experiments [6]. The interaction between positron and atom or molecule has also been widely studied to better understand how positrons interact with atomic electrons and are bound to them [7,8]. An experiment that measured positron-atom binding energies through the study of positron-atom recombination under a laser field was recently reported [9].Theoretical approaches to study these positron physics have been extensively developed [10]. Among them, two-component density functional theory (2C-DFT) [2,11], which is an extension of DFT [12] to the coupled electron-positron system, has been a powerful first-principles tool to calculate the ground-state electron and positron densities and their properties. 2C-DFT has been successfully applied to studies of positron interaction with atoms, solids and surfaces to determine the electron-positron momentum distributions [13], positron annihilation lifetimes [14], and positron binding energies [15], to name a few. Another powerful method is the wavefunction-based approach, such as the multi-component molecular orbital method [16] and quantum Monte Carlo method [17,18], which have also revealed much positron physics with high accuracy. However, the dynamical interaction mechanism between positrons and electrons, especially under a laser field [7-9], has not yet been clarified, because there has been no first-principles method that can simulate the correlated dynamics of positrons and electrons for realistic systems.In this study, we develop time-dependent multicomponent density functional theory (TDMCDFT) [19,20] toward an understanding of the mechanism of coupled electro...

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Full-correlation single-particle positron potentials for a positron and positronium interacting with atoms

Cited by 14 publications

References 42 publications

Modeling positronium beyond the single particle approximation

Modeling positronium beyond the single particle approximation

Pick-Off Annihilation of Positronium in Matter Using Full Correlation Single Particle Potentials: Solid He

Time-Dependent Multicomponent Density Functional Theory for Coupled Electron-Positron Dynamics

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