Self-energy of an electron due to electron-phonon interaction in alkali metals: Its dependence on phonon dispersion relation and realistic electron-electron screening

The electron mass-enhancement factor. lambda, due to election-phonon intel action, has been evaluated considering realistic description, both, for ele ctrons and phonons. Explicit analytical expressions for lambda have been de rived for dispersionless, highly dispersive and intermediately dispersive p honons when the electron screening is given by Thomas-Fermi model. Differen t types of electron screening which incorporate electron-electron interacti on much beyond Thomas-Fermi have also been considered. Computation of lambd a for all alkali metals have been made and compared with the corresponding experimental and other theoretical results.