Positronium chemistry by quantum Monte Carlo. I. Positronium-first row atom complexes

Bressanini, Dario; Mella, Mariella; Morosi, Gabriele

doi:10.1063/1.475887

Cited by 87 publications

(93 citation statements)

References 44 publications

(47 reference statements)

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“…The many-body wave functions of small positronic systems composed by a positron interacting with a light atom or a small molecule can be calculated to a good accuracy using the quantum Monte Carlo (QMC) [11][12][13][14][15][16] and configurationinteraction (CI) [17] methods. In this work, we have obtained accurate positron energies and densities for positronic atoms including a positron (e + H, e + He, e + Li, and e + Be) and Ps (HPs and LiPs) by an exact diagonalization stochastic variational method (SVM) using an explicitly correlated Gaussian (ECG) function basis set.…”

Section: Introductionmentioning

confidence: 99%

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

2014

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In this work we define single-particle potentials for a positron and a positronium atom interacting with light atoms (H, He, Li and Be) by inverting a single-particle Schrödinger equation. For this purpose, we use accurate energies and positron densities obtained from the many-body wavefunction of the corresponding positronic systems. The introduced potentials describe the exact correlations for the calculated systems including the formation of a positronium atom. We show that the scattering lengths and the low-energy s-wave phase shifts from accurate many-body calculations are well accounted for by the introduced potential. We also calculate self-consistent two-component density-functional theory positron potentials and densities for the bound positronic systems within the local density approximation. They are in a very good agreement with the many-body results, provided that the finite-positron-density electron-positron correlation potential is used, and they can also describe systems comprising a positronium atom. We argue that the introduced single-particle positron potentials defined for single molecules are transferable to the condensed phase when the inter-molecular interactions are weak. When this condition is fulfilled, the total positron potential can be constructed in a good approximation as the superposition of the molecular potentials.

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Section: Introductionmentioning

confidence: 99%

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

2014

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“…Further calculations on various positronic atoms quickly followed (see [3] for a review and [4][5][6][7][8] for more recent results). Besides of variational calculations with ECG functions, diffusion quantum Monte Carlo simulations appeared to be able to provide accurate energies for positronic systems [9][10][11][12][13]. Unfortunately, the computational cost of both methods increases quickly with the number of active electrons, limiting in practice their applicability to rather small atoms and molecules.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study of Positronic Atoms with Adiabatic Separation of Positronic Motion

Strasburger

Wołcyrz

2008

Acta Phys. Pol. A

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A modified adiabatic approximation, with the positron treated as a light nucleus and its charge included only partially in the electronic Hamiltonian, was applied to compute the energies and properties of bound states of lithium positride, positronic beryllium and positronic magnesium. The electronic Schrödinger equation was solved with the configuration interaction method. No bound state was obtained for lithium positride, while the dissociation energies of positronic beryllium and positronic magnesium were underestimated by 2.6 and 7 millihartrees, respectively. Consequences for the applicability of the adiabatic approximation to describe positronic systems are discussed.

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“…Three main all-body methods are worth to be cited. The powerful stochastic variational method (SVM) [1,2] and quantum Monte Carlo (QMC) [3][4][5] generated converged binding energies and annihilation rate constants † for small positronic atoms. However, they seem to have * e-mail: rachid@fisica.ufmg.br † During the meeting it was suggested by Prof. G. Duplâtre the use of the term "annihilation rate constant" instead of just "annihilation rate" since this last quantity is time dependent.…”

Section: Introductionmentioning

confidence: 99%

Is a Molecular Adiabatic Approximation Appropriate to Positronic Atoms and Molecules?

Mohallem

2008

Acta Phys. Pol. A

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The adiabatic approximation to positronic atoms and molecules was considered as an option to the computationally unfeasible methods that treat all particles in a common footing, in two different approaches communicated in the 37th PSPA. Here we present further assessment and comparison of the two approaches as a way of evaluating the potential of adiabatic or, as we found preferable, molecular approaches.

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Positronium chemistry by quantum Monte Carlo. I. Positronium-first row atom complexes

Cited by 87 publications

References 44 publications

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

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

Theoretical Study of Positronic Atoms with Adiabatic Separation of Positronic Motion

Is a Molecular Adiabatic Approximation Appropriate to Positronic Atoms and Molecules?

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