Exchange Interaction in SolidHe3

On the basis of our previous theory used to calculate the static properties of crystalline ${\mathrm{He}}^3$ and ${\mathrm{He}}^4$ at $T=0\mathrm{}$, we compute the exchange interaction of the nuclear spins in bcc ${\mathrm{He}}^3$ as a function of molar volume, obtaining good agreement with experiment. Comparison with the theories of Nosanow and co-workers and of Guyer and Zane shows that the success of the theory is mainly due to the effective-force constant used in the computations.