Adiabatic corrections of the helium dimer from exponentially correlated Gaussian functions

Exponentially correlated Gaussian wavefunctions are employed to compute the adiabatic (the diagonal Born–Oppenheimer) corrections of the helium dimer in its three isotopic forms: 4He2, 3He4He and 3He2. The corrections are evaluated for 0.0⩽R⩽15.0 bohr using the Born–Handy method. At equilibrium, the adiabatic correction causes a ∼0.01 K increase in the absolute value of the interaction energy of 4He2.