Implications of Parity and Time‐Reversal Symmetries in Atoms

Hsiang-Shun Chou ； Keh-Ning Huang

《Chinese Journal of Physics》 32卷2期 (1994/04) Pp. 171-193

並列摘要

We have investigated the implications of parity and time-reversal symmetries in atoms. The atomic wave function is expressed as a linear combination of configuration wave functions. If parity symmetry is violated, an atomic state no longer has a definite parity such that both electronic orbitals and configuration weight coefficients contain parity-nonconserving components. Time-reversal symmetry guarantees that the radial wave functions of the large and small components of the Dirac orbital differ in phase by ±π/2, and the parity-conserving and parity-nonconserving components of the Dirac orbital differ in phase by ±π/2 as well. In addition, time-reversal symmetry implies that the relative phases between parity-conserving configuration weight coefficients are 0 or π, while the relative phases between parity-conserving and parity-nonconserving configuration weight coefficients are ±π/2. The absence of permanent electric dipole moments of atoms with definite angular momentum is demonstrated. In addition, the Kramers theorem is elucidated explicitly in the relativistic context. In the multipole expansion of the photon field, the relative phases between the expansion coefficients for the transverse electric multipole potentials and for the magnetic or longitudinal electric multipole potentials are ±π/2. Finally, we show that the relative phases between competing transition amplitudes are 0 or π, which leads to constructive or destructive interferences between competing atomic transitions.