Nonadiabatic variational calculations on dipositronium using explicitly correlated Gaussian basis functions

Journal Article · Sat May 01 00:00:00 EDT 1993 · Physical Review A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.47.3671· OSTI ID:6872879

Kinghorn, D B; Poshusta, R D ^[1]

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1. Department of Chemistry, Washington State University, Pullman, Washington 99164-4630 (United States)

Nonadiabatic variational calculations are described for dipositronium ([ital e][sup +],[ital e][sup +],[ital e][sup [minus]],[ital e][sup [minus]]) using explicitly correlated Gaussian basis functions with angular momentum zero. An improved rigorous upper bound for the [ital A][sub 1] ground-state energy for dipositronium is achieved ([minus]0.515 976 7 a.u.) leading to a corresponding bound for the binding energy, [Delta][var epsilon][sub 0][gt]0.435 eV, which is greater than previous estimates by 0.024 eV. This improved energy is obtained by exploiting the full permutational symmetry of the Hamiltonian including charge-reversal symmetry which was ignored in recent calculations. The first excited [ital A][sub 1] state, and the lowest [ital B][sub 1] and [ital A][sub 2] states of dipositronium are found to be unbound while the [ital B][sub 2] and [ital E] states appear to be metastable. For comparison, by the same method, the [sup 2][ital S] ground-state energy of the lithium atom is found to be [minus]7.476 716 1 a.u., which lies 0.001 343 a.u. above the accepted true energy. Expectation values for individual terms of the Hamiltonian along with moments of interparticle distances [l angle][ital r][sup [plus minus]1][r angle], [l angle][ital r][sup [plus minus]2][r angle], and [l angle][delta]([ital r][sub [ital i][ital j]])[r angle] are also reported.

• OSTI ID: 6872879
• Journal Information: Physical Review A; (United States), Vol. 47:5; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
POSITRONIUM
BINDING ENERGY
ANGULAR MOMENTUM
C INVARIANCE
COMPARATIVE EVALUATIONS
DIMERS
ELECTRONIC STRUCTURE
EXCITED STATES
GAUSS FUNCTION
GROUND STATES
LITHIUM
VARIATIONAL METHODS
ALKALI METALS
CALCULATION METHODS
ELEMENTS
ENERGY
ENERGY LEVELS
EVALUATION
FUNCTIONS
INVARIANCE PRINCIPLES
METALS
664500* - Special Atoms & Molecules- (1992-)