Migdal A. Approximation Methods in Quantum Mechanics 1969 torrent

Textbook in PDF format

If an expert mathematical physicist (or two) combined all his lifelong tips and tricks and put them into one volume, this book would be the outcome. The problems are extremely interesting (approximate the size of a hydrogen atom based purely on dimensional arguments…, Pair formation, Lamb Shift, Photoelectric effect…). These are all solved by using qualitative physical arguments (‘small’ perturbations, ‘sudden’ perturbations etc.). Estimating derivatives, integrals and solutions to Differential Equations – are all part of their toolkit. After discussing a particular approximation technique, the authors apply them to recover some fundamental results of QED or Quantum Mechanics.
The book describes very simple approximation methods of Quantum Mechanics with remarkable clarity. For those who appreciate quick, by-hand estimates of results, this is truly a gift from heaven!