Chemical bond and entanglement of electrons in the hydrogen molecule
  We theoretically investigate the quantum correlations (in terms of concurrence of indistinguishable electrons) in a prototype molecular system (hydrogen molecule). With the assistance of the standard approximations of the linear combination of atomic orbitals and the configuration interaction methods we describe the electronic wavefunction of the ground state of the H2 molecule. Moreover, we managed to find a rather simple analytic expression for the concurrence (the most used measure of quantum entanglement) of the two electrons when the molecule is in its lowest energy. We have found that concurrence does not really show any relation to the construction of the chemical bond. 
Nikos Iliopoulos (1) and Andreas F. Terzis (1) ((1) School of Natural   Sciences, University of Patras, Greece)
quant-ph