Converting hyperfine splitting constants (HFSCs, \(a\) values in mT)
  into hyperfine coupling ones (HFCCs, \(A\) values in MHz).
Details
Conversion performed according to the following relation:
  $$A = (a\,g\,\mu_{\text{B}}) / h$$
  where \(h\) corresponds to Planck's constant and \(\mu_{\text{B}}\) to Bohr's magneton.
  Both latter are obtained by the constans::syms$h and constants::syms$mub, respectively,
  using the constants package (see syms).
  Conversion is suitable for the EPR simulations and/or ENDOR.
See also
Other Conversions and Corrections:
convert_A_MHz_2a(),
convert_B(),
convert_time2var(),
correct_time_Exp_Specs()