The hindered rotor theory: A review

Hindered rotations are common in nature and can greatly affect thermodynamic properties. Typically, the standard rigid-rotor harmonic-oscillator approximation is used to compute thermodynamic properties; however, it often leads to serious errors, particularly for molecules with hindered rotations. Hence, to reach accurate thermodynamic predictions for such cases, the hindered rotor approximation must be applied. Different methods to compute thermodynamic properties for molecules with hindered rotations are available. Herein, we review the theoretical basis of different methods, their accuracy, and applicability. We also present the different algorithms to identify hindered rotors and obtain the input parameters for the hindered rotor model, and the software available to compute thermodynamic properties under this scheme. This article is categorized under: Structure and Mechanism > Molecular Structures Theoretical and Physical Chemistry > Reaction Dynamics and Kinetics