A survey on homological perturbation theory

First we describe in detail the general setting in which we represent the mathematics of Kenzo: dependent type theory with universes, essentially the system [11], with a

If the cluster operator ˆ T is not truncated, the CC wave function is just a nonlinear reparametriza- tion of the FCI wave function: optimizing the cluster amplitudes t = (t r a , t

First we construct an infinite sequence of rational curves on a generic quintic V such that each curve has negative normal bundle.. Then we deform to quintics with nodes in such a

Besides regular fields which may be slightly more general than those deriving from a non degenerate Lagrangian, the only case which has been looked at is that of the Maxwell field F

A priori, there is no guarantee that this series will provide the smooth convergence that is desirable for a systematically im- provable theory. In fact, when the reference HF

The classical results of Density Functional Perturbation Theory in the non-degenerate case (that is when the Fermi level is not a degenerate eigenvalue of the mean-field

(4) and (5) show that instead of the usual "decoupliig'; between ionization balance and excited states populatior~ justified by time scales, a formal decoupling is

This theory is based on the Feshbach-Schur map and it has advantages with respect to the stan- dard perturbation theory in three aspects: (a) it readily produces rigorous estimates