TY  - BOOK
AU  - Kleiss,Ronald
TI  - Quantum field theory: a diagrammatic approach 
SN  - 9781108486217
AV  - QC174.45 .K58 2021
U1  - 530.143 K67Q 23
PY  - 2021///
CY  - Cambridge
PB  - Cambridge University Press
KW  - Quantum field theory
N1  - Includes bibliographical references and index
N2  - "Let us first consider a general Hamiltonian of Z electrons moving around a nucleus that contains the Coulomb interaction, the spin-orbit coupling, and the hyperfine coupling. These are the three effects that determine the electronic structure of an atom. Here we should emphasize the important role of the separation of energy scales; that is to say, the typical energy scales of these three terms are quite different. Thanks to the separation of energy scales, we can analyze them one by one, which enables us to obtain a clear picture of the electron structure"--
ER  -