Maximum Entropy Methods of Analytic Continuation.

One well known problem with QMC is that it generally produces results as a function of imaginary time $\tau$; whereas, most experiments measure dynamical quantities which are functions of real frequency $\omega$. We recently developed a successful maximum entropy method (MEM) of analytic continuation of data from imaginary time to real frequencies. Our method greatly enhances the usefulness of QMC simulations. We applied this method to the problem of transport and photoemission in the dilute magnetic alloy, demonstrated the Haldane conjecture for 1-d quantum spin chains, and demonstrated the dynamical scaling of 2-d quantum spin-1/2 antiferromagnets, and to study the dynamics of infinite-dimensional lattice models discussed above, etc. Together with Jim Gubernatis, I have written a highly cited review of this method. In addition, the application of these methods to optimize experiments has led to additional external funding from industry and ORNL.