Relativistic and Quantum Electrodynamics Effects in the Helium Pair Potential

The helium pair potential was computed including relativistic and quantum electrodynamics contributions as well as improved accuracy adiabatic ones. Accurate asymptotic expansions were used for large distances $R$. Error estimates show that the present potential is more accurate than any published to date. The computed dissociation energy and the average $R$ for the ${}^4\mathrm{He}_2$ bound state are $1.62\pm 0.03\mathrm{mK}$ and $47.1\pm 0.5\AA$. These values can be compared with the measured ones: ${1.1}_{-0.2}^{+0.3}\mathrm{mK}$ and $52\pm 4\AA$ [R. E. Grisenti et al., Phys. Rev. Lett. 85, 2284 (2000)].