Published in Phys. Rev. B, 2020
We calculated the momentum distribution n(k) of BCC lithium using all-electron QMC in the grand-canonical ensemble. Kinetic sum rule from finite-size corrected n(k) agrees with thermodynamic limit to 0.1 mha/e. BFD solid - liquid difference agrees well with experiment, but the pseudopotential Compton profile is too narrow due to lack of orthogonalization with core states.