Abstract
A first principle calculation for frequencies of phonons propagating in three symmetry directions in metallic Li is presented. The ion-electron interaction potential is constructed entirely from the Slater type of atomic core orbitals. The results obtained on the Hartree field and Hartree-Slater potential reveal the importance of core-valence exchange potential to predict the cross-over between longitudinal and transverse phonon branches in the ( zeta 00) direction.