Magnetic-field effects in transitions of X Li molecules (X: even isotopes of group II atoms)

We analyze the Zeeman shift in the (nu, N) = (0,0) -> (1,0) transition frequency of X Li molecules (X: even isotopes of group II atoms), which is of interest in metrology. The Zeeman shift in the transition frequency between stretching states is found to be less than 1 mHz with a magnetic field of 1 G. X Li-6 molecules are more advantageous than X Li-7 molecules for measuring the transition frequency without the Zeeman shift because of the smaller g factor of the Li nuclear spin.