NONADIABATIC VARIATIONAL CALCULATIONS ON DIPOSITRONIUM USING EXPLICITLY CORRELATED GAUSSIAN-BASIS FUNCTIONS

被引:116
作者
KINGHORN, DB
POSHUSTA, RD
机构
来源
PHYSICAL REVIEW A | 1993年 / 47卷 / 05期
关键词
D O I
10.1103/PhysRevA.47.3671
中图分类号
O43 [光学];
学科分类号
070207 ; 0803 ;
摘要
Nonadiabatic variational calculations are described for dispositronium (e+,e+,e-,e-) using explicitly correlated Gaussian basis functions with angular momentum zero. An improved rigorous upper bound for the A1 ground-state energy for dipositronium is achieved (-0.5159767 a.u.) leading to a corresponding bound for the binding energy, DELTAepsilon0 > 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 A1 state, and the lowest B1 and A2 states of dipositronium are found to be unbound while the B2 and E states appear to be metastable. For comparison, by the same method, the 2S ground-state energy of the lithium atom is found to be -7.476716 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 [r+/-1], [r+/-2], and [delta(r(ij))] are also reported.
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页码:3671 / 3681
页数:11
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