Accurate Vibrational and Ro Vibrational Contributions to the Properties of Large Molecules by a New Engine Employing Curvilinear Internal Coordinates and Vibrational Perturbation Theory to Second Order Journal of Chemical Theory and Vibrational couplings and energy transfer pathways of water's bending mode Nature Communications Vibration Rotation Spectrum of HCl Vibration Rotation Spectra, the Coriolis Coupling Constants and the Intramolecular Force Field of Symmetric Top Molecules. I. Th Rovibrational spectroscopy