Multi-dimensional potential energy surfaces spanned in terms of normal coordinates - as computed with the SURF program -
can now be rotated or transformed into an arbitrary set of normal coordinates. This allows for the efficient calculation of
Franck-Condon factors or the calculation of vibrational spectra of isotopologues from just one potential energy surface
[P. Meier, D. Oschetzki, R. Berger and G. Rauhut, J. Chem. Phys. 140, 184111 (2014)].