A program to compute the angular coefficients of the relativistic one-electron hyperfine structure parameters Original Research Article

The Chfs program calculates the angular coefficients αksk1 and βksklnl of the relativistic one-electron hyperfine structure parameters for the case of pure SL-coupling or, alternatively, the case of intermediate coupling. The calculation is based on SL-basis states and, optionally, mixing coefficients of the electronic wave functions of atoms. The derivation of the necessary matrix elements is based on the effective tensor operator formalism; explicit expressions are cited. Chfs is the first program which is able to compute the angular coefficients for electronic configurations with up to four electron shells.