Accuracy of the finite-temperature Lanczos method compared to simple typicality-based estimates

摘要: We study trace estimators for equilibrium thermodynamic observables that rely on the idea of typicality and derivatives thereof such as finite-temperature Lanczos method (FTLM). As numerical examples quantum spin systems are studied. Our initial aim was to identify pathological or circumstances, strong frustration unusual densities states, where these methods could fail. Instead we failed with attempt. All investigated allow approximations, only at temperatures order lowest energy gap convergence is somewhat slower in number random vectors over which averaged.