  Polar diatomic molecules that have, or are expected to have a
$^2\Sigma_{1/2}$-ground state are studied systematically with respect to
simultaneous violation of parity $\mathcal{P}$ and time-reversal $\mathcal{T}$
with numerical methods and analytical models. Enhancements of
$\mathcal{P,T}$-violating effects due to an electric dipole moment of the
electron (eEDM) and $\mathcal{P,T}$-odd scalar-pseudoscalar nucleon-electron
current interactions are analyzed by comparing trends within columns and rows
of the periodic table of the elements. For this purpose electronic structure
parameters are calculated numerically within a quasi-relativistic zeroth order
regular approximation (ZORA) approach in the framework of complex generalized
Hartree-Fock (cGHF) or Kohn-Sham (cGKS). Scaling relations known from analytic
relativistic atomic structure theory are compared to these numerical results.
Based on this analysis, problems of commonly used relativistic enhancement
factors are discussed. Furthermore the ratio between both $\mathcal{P,T}$-odd
electronic structure parameters mentioned above is analyzed for various groups
of the periodic table. From this analysis an analytic measure for the
disentanglement of the two $\mathcal{P,T}$-odd electronic structure parameters
with multiple experiments in dependence of electronic structure enhancement
factors is derived.
