The next simplest vdW system exhibiting bonding between neutral hydrogen atoms is the hydrogen molecule dimer. Here, the full-dimensional potential-energy surface is rather complex. However, several specific configurations exist where the intramolecular structure of two hydrogen molecules is conserved, and the binding of the two monomers is dominated by vdW forces. For this study, we have selected the collinear, parallel, perpendicular, and shifted parallel configurations (see Figure ), given that previous SAPT analyses indicate that their equilibrium geometry is caused by a balance between exchange and dispersion interactions. The equilibrium distances for hydrogen molecule dimers are summarized in Table , as well as the relative contributions of each SAPT2+3(CCD) force component. The intramolecular H-H distance was fixed at 0.74 Å. Regarding the SAPT force decomposition, it can be concluded that the collinear and parallel configurations are the arrangements where two hydrogen molecules interact mostly due to the balance of dispersion and exchange forces. Contrary to perpendicular and shifted parallel configurations, where the electrostatic component is TABLE I. Equilibrium distances (in Bohrs) for the hydrogen molecule dimers and atomic probes obtained with CCSD(T)/CBS and SAPT2+3(CCD)/aug-cc-pVQZ. Also shown is the ratio of each SAPT force with respect to the total attractive F-or repulsive forces F+. The largest force ratio for each group is highlighted in bold.