Nonequilibrium Green's functions (NEGF) have emerged as a pivotal theoretical framework for investigating the time-dependent behaviour of quantum many-body systems. By tracking the evolution of ...

We show that the Green functions on flat tori can have either three or five critical points only. There does not seem to be any direct method to attack this problem. Instead, we have to employ ...

The conditioning of spline collocation matrices is considered in the case of a boundary value problem for an mth order equation. For bases with continuity built in (which corresponds to most current ...