That said, a sample of Palladium of volume V is "charged" (through an electrochemical process) with deuterium. For our purposes, we refer to N pairs of deuterons. We schematize this system of N pairs, through an ideal gas, i.e. whose constituents do not interact. Following the standard approach for the study of these problems, we write the Hamiltonian operator of a single constituent (that is, of a single pair of deuterons). Since the single deuteron has electric charge e (where e>0 is the absolute value of the electron charge), the elements of a single pair interact through a repulsive Coulomb potential. Precisely, with obvious meaning of the terms
with
Turning to the relative coordinate system and the center of mass, and neglecting the motion of the latter: