Hartmut-Loewen.pdf

approximations on different levels
1) LDA LDA, llocal l density d i approximation: i i
where is the excess free energy density in a homogeneous (bulk)
system, input, valid only for small inhomogeneites
2) LDA + mean field:
with
� homogeneous limit is respected valid for ”moderate“ inhomogeneites, but not
for density variations on the microscopic scale