  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.
