A framework is proposed for studying in a Lorentz covariant manner the Ehrenfest-type classical limit of the Dirac equation with an external electromagnetic field. We reformulate the Dirac equation using a Lorentz-invariant proper-time coordinate in Minkowski space-time and we propose a new kind of expectation values which are Lorentz covariant. Next, we give an example of a Lorentz- and gauge-covariant, bispinorial wave packet moving along a given classical trajectory. Finally, we obtain Lorentz-covariant classical equations of motion for a spin-1/2 particle in an inhomogeneous electromagnetic field. The classical equations of motion are a result of a consistency condition.
Spectroscopic amplitudes are calculated for a transfer of two nucleons in the (\(S, T = 1.0\)) and (0,1) states between low-lying, normal parity states of 1 p-shell nuclei. Calculations are performed with the intermediate-coupling model wavefunctions of nuclei considered. The wavefunctions were generated using the interaction parameters of Cohen and Kurath. These spectroscopic amplitudes are necessary for a description of two-nucleon transfer in one of intermediate steps of the multi-step sequential transfer process. Sum rules for the calculated spectroscopic amplitudes are given.
