Isoelectronium correlations as a nonlinear two-dimensional two-particle   tunnel effect
  In this paper, we study a nonlinear two-dimensional two-particle quantum tunnel effect with dissipation in diatomic H-H system. We use an instanton technique based on the path integral approach, and present analytical solutions, in the approximation of linearized reaction coordinates and harmonic potential. It appears that the tunnel effect leads to a specific correlation between two electrons interacting with each other by Coulomb potential. This effect can be viewed as a mechanism supporting the isoelectronium state recently proposed by Santilli and Shillady within the framework of isochemical model of the hydrogen molecule. We show that, under a condition of effective two-dimensional motion, contribution of the quantum tunnel correlated configurations is essential in the electron dynamics. Temperature dependence of the probability of the two-electron tunnel transitions per unit time has been studied. 
A. K. Aringazin, M. B. Semenov