Quantum Monte Carlo calculations of bulk Li

Using all-electron fixed-node quantum Monte Carlo methods we calculate equations of states for ambient and high pressure phases of Li using the structural data from experimental observations up to high pressures.\footnote[1]{M.~Hanfland, K.~Syassen, N.~E.~Christensen, and D.~L.~Novikov, Nature 408, 174--178 (2000).} We compare the suitability of orbital sets from several Density Functional Theory functionals for use in many-body trial Slater-Jastrow wave-functions. We reduce finite-size errors by utilizing twist-averaging\footnote[2]{C.~Lin, F.~H.~Zhong, and D.~M.~Ceperley, Phys. Rev. E 64, 016702 (2001).} and by structure factor correction for several sizes of simulation cell.\footnote[3]{S.~Chiesa, D.~M.~Ceperley, R.~M.~Martin, and M.~Holzmann, Phys. Rev. Lett. 97, 076404 (2006).}