Critical behavior of screened one-electron diatomic molecules

FEDERICO PONT; PABLO SERRA

Santos

Conferencia; 18th International IUPAP Conference on Few-Body Problems in Physics (fb18); 2006

IUPAP

Recently  very interesting results had been obtained about the borromean  nature of some quantum few body systems. This systems present the particularity of being stable, i.e. they have weakly bound states, even though all posible subsystems are unstable. The most simple molecular physics system is  treated: H^+_2-like system, when the particles interact through the screened Coulomb  potential  (Yukawa potential). Within this work we study the one electron homonuclear diatomic molecules  with the screened interaction. Particularly the Hamiltonian and the  ground-state energy depend on the  parameters$(\eta=m_{charge}/M_{nuc},\lambda=q_{charge}/Q_{nuc},\sigma)$. We study the critical behavior of the system [2] through the estimation of critical screening parameter $\sigma_{c}(\eta,\lambda)$,  at wich the system lose the  (bound)  ground-state, i.e. the molecule dissociates. We also study the critical exponent $\alpha$ [2], wich is related to the asymptotic behavior of the energy $E_{0}(\sigma)\sim-(\sigma_c-\sigma)^{\alpha}$ for $\sigma \downarrow \sigma_c$. These near-threshold properties are  studied for both, borromean and non borromean regions as a function of the parameters