Ladder of Density Functional Approximations: How High Can We Climb?

John P. Perdew, Department of Physics, Tulane University, New Orleans, LA

The density functional theory of Kohn and Sham replaces the complicated problem of the many-electron ground state by a simpler but formally-equivalent problem of non-interacting electrons. This theory is now so widely used that it is the citation leader of both physics and chemistry. This talk will address the problem of the nonempirical construction of density functional approximations to the exchange-correlation energy. These approximations may be assigned to various rungs of "Jacob's Ladder," on which higher rungs employ richer local ingredients, satisfy more exact constraints, and achieve higher accuracy. Each rung is built upon and incorporates the lower rungs. After a discussion of the first three completed rungs (local spin density approximation, generalized gradient approximation or GGA, and meta-GGA), the possibilities for the fourth and fifth "dream rungs" will be discussed.

The P/T Colloquium is
typically held each
Thursday, 3:45–5:00 PM.
Refreshments are served
at 3:15 PM.