Critical Behavior of screened one-electron diatomic mólecules

PONT F. M.; PABLO SERRA

Capital Federal Buenos Aires - Argentina

Workshop; Eighth Giambiagi Winter School (Part A) - Cluster, Molecules, Biomolecules and Materials; 2006

Departamento de Física - Facultad de Ciencias Exactas Físicas y Naturales - Universidad Nacional de Buenos Aires

Recently [1] very interesting results had been obtained about the borromean nature of some quantum few body systems. These systems present the particularity of being stable, i. e. they have weakly bound states, even though all possible subsystems are unstable. In [1], the most simple molecular physics system is treated: H^{+}_2 - like system, when the particles interact through the screened Coulomb potential exp(-sigma r)/r (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 the critical screening parameter sigma_c(eta,lambda), at wich the system loses 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)=-(sigma-sigma_c)^{alpha} for sigma->sigma_c. These near-threshold properties are studied for both, borromean and non borromean regions as a function of the parameters eta and lambda.1. L. Bertini et al. Phys. Rev. A, 69, 042504 (2004).2. S. Kais and P. Serra, Adv. Chem. Phys. 125, 1 (2003).