  A new method is proposed to calculate the polarization vector of a molecule
in a monochromatic external field in the anomalous-despersion domain. The
method takes into account the instantaneous switching of the field. A simple
modification of the method allows one to consider a more general switching
procedure. As an illustration of the method Fourier components of the
polarization vector of the LiH molecule in the anomalous -dispersion domain is
calculated.
