Stability of four-unit-charge systems: A quantum Monte Carlo study
| Autor: | Dario Bressanini, G. Morosi, Massimo Mella |
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| Rok vydání: | 1997 |
| Předmět: | |
| Zdroj: | Physical Review A. 55:200-205 |
| ISSN: | 1094-1622 1050-2947 |
| DOI: | 10.1103/physreva.55.200 |
| Popis: | The family of four-particle systems ( M 1 m 1 M 2 m 2 ) has been studied by means of Monte Carlo techniques. Nonadiabatic explicitly correlated wave functions for different values of the mass ratio M/m have been obtained using a variational Monte Carlo optimization method. These wave functions have been used in diffusion Monte Carlo simulations of ( M 1 m 1 M 2 m 2 ) to compute exact ground-state energies. Our results enlarge the stability range of the mass ratio for these and for similar less symmetric systems and address the problem of the stability of the hydrogen-antihydrogen system. For the special case of the dipositronium molecule (M5m) we report the ground-state energy, consistent with previous accurate calculations, and average values of various observables. @S1050-2947~97!05901-5# In the last few years attention has been paid to the stability problem of three @1‐3# and four @4‐15# unit-charge systems. Accurate results for the energy and other expectation values have been computed using a nonadiabatic description. These results helped to clarify the structure of these systems and to understand matter-antimatter annihilation. Investigations in this field are also concerned with the mass dependence of the complex mechanism driving the matter to build large aggregates of particles instead of splitting into smaller pieces @2,4,14#. In molecular physics stability is usually defined in the framework of the Born-Oppenheimer approximation, exploiting the small ratio between electronic and nuclear masses. This possibility is lost if the mass ratio is close to one, and in such a case it is necessary to adopt a nonadiabatic |
| Databáze: | OpenAIRE |
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