  As local density approximation positron calculations systematically
underestimate positron lifetimes when they are compared with their experimental
counterparts, the generalized gradient approximation (GGA) for positrons was
introduced in the 1990s, in analogy with the GGA for electrons. New
developments in the GGA for positrons are summarized and presented here and it
is also discussed how they affect and possibly improve calculated positron
lifetimes. In particular, these new GGA approaches are based on the recent
perturbed hypernetted-chain and quantum Monte Carlo results.
