Lifetime of Positronium Molecule. Study with Boys' Explicitly Correlated Gaussians

Kozłowski, Pawel M.; Adamowicz, Ludwik

doi:10.1021/jp9528166

Cited by 26 publications

(8 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recent calculations, which include relativistic corrections, yield 0.4341373 eV [508]. The ground state Ps 2 lifetime has also been calculated many times [510,576,578,579], with a recent value of 0.22455(6) ns [580]. Ps 2 molecules consist of a pair of oppositely polarized Ps spin configurations.…”

Section: Ps 2 Spectroscopymentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

View full text Add to dashboard Cite

Abstract. The field of experimental positronium physics has advanced significantly in the last few decades, with new areas of research driven by the development of techniques for trapping and manipulating positrons using Surko-type buffer gas traps. Large numbers of positrons (typically ≥10 6 ) accumulated in such a device may be ejected all at once, so as to generate an intense pulse. Standard bunching techniques can produce pulses with ns (mm) temporal (spatial) beam profiles. These pulses can be converted into a dilute Ps gas in vacuum with densities on the order of 10 7 cm −3 which can be probed by standard ns pulsed laser systems. This allows for the efficient production of excited Ps states, including long-lived Rydberg states, which in turn facilitates numerous experimental programs, such as precision optical and microwave spectroscopy of Ps, the application of Stark deceleration methods to guide, decelerate and focus Rydberg Ps beams, and studies of the interactions of such beams with other atomic and molecular species. These methods are also applicable to antihydrogen production and spectroscopic studies of energy levels and resonances in positronium ions and molecules. A summary of recent progress in this area will be given, with the objective of providing an overview of the field as it currently exists, and a brief discussion of some future directions.

show abstract

Section: Ps 2 Spectroscopymentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

View full text Add to dashboard Cite

show abstract

“…[1][2][3] Perhaps, the most important conclusion of those studies is the crucial contribution of the electron-positron (e-p) dynamical correlation to positron binding. Explicitly correlated Gaussian (ECG) methodologies, [4][5][6][7][8] quantum Monte Carlo (QMC), [9][10][11] and full configuration interaction (FCI) 12,13 methods have demonstrated superior performance in the description of e-p correlation and the estimation of positron binding energies, PBEs. Despite their proven accuracy, these approaches are extremely computationally demanding and calculations are only feasible for relatively small systems, namely, atoms, [14][15][16][17][18][19] diatomic molecules, 18,[20][21][22][23] and linear triatomics.…”

Section: Introductionmentioning

confidence: 99%

Calculation of positron binding energies using the generalized any particle propagator theory

Romero

Charry

Flores‐Moreno

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

We recently extended the electron propagator theory to any type of quantum species based in the framework of the Any-Particle Molecular Orbital (APMO) approach [J. Romero, E. Posada, R. Flores-Moreno, and A. Reyes, J. Chem. Phys. 137, 074105 (2012)]. The generalized any particle molecular orbital propagator theory (APMO/PT) was implemented in its quasiparticle second order version in the LOWDIN code and was applied to calculate nuclear quantum effects in electron binding energies and proton binding energies in molecular systems [M. Díaz-Tinoco, J. Romero, J. V. Ortiz, A. Reyes, and R. Flores-Moreno, J. Chem. Phys. 138, 194108 (2013)]. In this work, we present the derivation of third order quasiparticle APMO/PT methods and we apply them to calculate positron binding energies (PBEs) of atoms and molecules. We calculated the PBEs of anions and some diatomic molecules using the second order, third order, and renormalized third order quasiparticle APMO/PT approaches and compared our results with those previously calculated employing configuration interaction (CI), explicitly correlated and quantum Montecarlo methodologies. We found that renormalized APMO/PT methods can achieve accuracies of ~0.35 eV for anionic systems, compared to Full-CI results, and provide a quantitative description of positron binding to anionic and highly polar species. Third order APMO/PT approaches display considerable potential to study positron binding to large molecules because of the fifth power scaling with respect to the number of basis sets. In this regard, we present additional PBE calculations of some small polar organic molecules, amino acids and DNA nucleobases. We complement our numerical assessment with formal and numerical analyses of the treatment of electron-positron correlation within the quasiparticle propagator approach.

show abstract

“…Slater‐type functions (STFs) for the protons were adopted. Since then, several groups 6–26 attempted to develop the non‐BO theory. There, the compatibility of accuracy and feasibility has been an open problem.…”

Section: Introductionmentioning

confidence: 99%

Nuclear orbital plus molecular orbital theory: Simultaneous determination of nuclear and electronic wave functions without Born–Oppenheimer approximation

Nakai

2007

Int J of Quantum Chemistry

100

View full text Add to dashboard Cite

ABSTRACT:We review a recent development in a rigorous non-Born-Oppenheimer method, i.e., nuclear orbital plus molecular orbital (NOMO) method, which determines the nuclear and electronic wave functions simultaneously. The NOMO theory is an exact theory for the non-BO problem in principle; for example, full-configuration interaction formulation for a complete configuration space. Hartree-Fock (HF) equations for NOs and MOs are derived for practical calculations. The usage of Gaussian basis functions for NOs is discussed. We formulate the elimination of translational and rotational contaminations in the NOMO method. Further, many-body effect such as nucleus-nucleus (n-n), nucleuselectron (n-e), and electron-electron (e-e) correlations are investigated by applying the second-order Møller-Plesset perturbation theory to the NOMO method. The excited-state theories such as configuration interaction and generator coordinate methods are examined to describe not only electronic but also vibrational excited states.

show abstract

Lifetime of Positronium Molecule. Study with Boys' Explicitly Correlated Gaussians

Cited by 26 publications

References 26 publications

Experimental progress in positronium laser physics

Experimental progress in positronium laser physics

Calculation of positron binding energies using the generalized any particle propagator theory

Nuclear orbital plus molecular orbital theory: Simultaneous determination of nuclear and electronic wave functions without Born–Oppenheimer approximation

Contact Info

Product

Resources

About