CMT seminar: The generalized gradient approximation in ultracold atomic physics

Monday, May 23, 2011 – 3:15pm – 4:30pm
Reiss 261A
Hulikal Krishnamurthy
Indian Institute of Science

I will describe ideas we have been working on generalizing the local density approximation to take into account the changes due to the gradients of the Green’s functions at each lattice site, similar to how gradient approximations are added to density functional theory. I will illustrate examples of how this approach works by showing order-disorder transitions in the two dimensional Falicov-Kimball model in a trap and calculations of the entropy per particle of the three dimensional Hubbard model in a trap. In general, we find the LDA and GGA are very accurate at high temperature up to the Tc for a phase transition, but often fail significantly near the critical point. The results for the GGA are not significantly different from the LDA in equilibrium. In nonequilibrium, however, we expect significant differences between the two approaches.

Host: Jim Freericks