  Molecular line intensity calculations are not a straightforward task. We
present a description of the basics for including molecular linesin synthetic
spectra, and of the input data needed. We aim both at describing ways in which
molecular lines are computed in the context of photospheres of F-G-K stars, and
to present a new online available version of our code for spectrum synthesis of
cool stars. We apply calculations to molecular bands in the ultraviolet,
visible and near-infrared main features, and comparisons with spectra of
reference stars are shown. We provide user-friendly tools for the free use of
the code PFANT. The code is available at http://trevisanj.github.io/PFANT.
