Path-integral Monte Carlo calculation of the kinetic energy of condensed lithium

We report path-integral Monte Carlo calculations of the kinetic energy of condensed lithium for several temperatures in both the solid and liquid phases. The excess kinetic energy of lithium decreases from about 10.4% of the classical value at 300 K to 3.2% at 520 K indicating a very slow decay with temperature. A Wigner-Kirkwood perturbation treatment of quantum effects to order ${\ensuremath{\Elzxh}}^{2}$ gives a satisfactory agreement with the path-integral results.