Energy spectrum of an artificial molecular complex in toroidal quantum rings

A model of an artificial hydrogen molecule consisting of two on-axis ionized donors and two electrons furnished by them inside a narrow quantum ring under the presence of an external magnetic field is considered. By using the adiabatic approximation, the lowest-energy states as a function of the separation between donors are calculated and compared with similar curves for the hydrogen molecule. In contrast to the single properties imposed by nature on the actual hydrogen molecule, our model allows us to explore a great variety of properties of the artificial hydrogen molecule by changing the ring dimensions.