title: Electronic interactions in the expanded metal compound Li-NH3.
abstract: Inelastic x-ray scattering was used to measure the plasmon as a function of electron density in liquid lithium ammonia as well as the low temperature solid phase. As the electronic density is lowered, electronic correlation effects cause the random-phase approximation (RPA) to break down, requiring more advanced theoretical treatments. The deviation from RPA becomes greatest at the lowest electronic densities. We also see evidence for decreased electronic screening as shown by an increase in the strength of the pseudopotential at lower concentrations. Plasmon behavior in the solid is similar to that of the heavier alkali metals, but surprisingly different than in the liquid.
authors.affiliation: Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Burns
authors.forename: P
authors.initials: P
authors.lastname: Giura
authors.forename: A
authors.initials: A
authors.lastname: Said
authors.forename: A
authors.initials: A
authors.lastname: Shukla
authors.forename: G
authors.initials: G
authors.lastname: Vankó
authors.forename: M
authors.initials: M
authors.lastname: Tuel-Benckendorf
authors.forename: E D
authors.initials: ED
authors.lastname: Isaacs
authors.forename: P M
authors.initials: PM
authors.lastname: Platzman