The coefficient Bx(n; T) that determines the leading gradient contributions at finite temperature, T, to the nonlocal exchange free energy of a system of fermions interacting by a static screened Coulomb interaction u2(r) = (e2/r) e−λr has limiting behavior for small λ and T, which depends on the order in which the limits λ → 0 and T → 0 are taken. We isolate the quantity that is responsible for this nonuniformity of limits and present a numerical study of its dependence on λ and T. The physical reason for different limiting values of Bx(n; T) is given. We consider the applicability of these results to physical systems and also discuss the discrepancy between first principles and semiempirical determinations of the leading gradient expansion coefficient for the nonlocal ground-state exchange energy of atoms.
Nonlocal exchange contribution to the free energy of inhomogeneous many-fermion systems. III: Numerical study for screened Coulomb interaction
NEILSON, DAVID
1994-01-01
Abstract
The coefficient Bx(n; T) that determines the leading gradient contributions at finite temperature, T, to the nonlocal exchange free energy of a system of fermions interacting by a static screened Coulomb interaction u2(r) = (e2/r) e−λr has limiting behavior for small λ and T, which depends on the order in which the limits λ → 0 and T → 0 are taken. We isolate the quantity that is responsible for this nonuniformity of limits and present a numerical study of its dependence on λ and T. The physical reason for different limiting values of Bx(n; T) is given. We consider the applicability of these results to physical systems and also discuss the discrepancy between first principles and semiempirical determinations of the leading gradient expansion coefficient for the nonlocal ground-state exchange energy of atoms.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.