Quantum mechanical approach to IR intensities via nuclear electric shielding tensors. I. Water.

The connection between the nuclear electric shielding and the atomic polar tensors are shown. The electric shielding tensors are related to the polarizability and the magnetizability, and satisfy a constraint condition for the electrostatic equilibrium which is the mixed length-acceleration Thomas–Reiche–Kuhn sum rule. In addition, they can be successfully used to rationalize experimental IR intensity data, which is verified by extended basis set calculations on the water molecule.