Zero-Point and Finite Temperature Vibrational Averaging

3 Zero-Point and Finite Temperature Vibrational Averaging 

Under certain conditions it can be expected that vibrational effects play an important role in the chiroptical response of a molecule. For example, vibrational effects might be important when [176]  

The molecule becomes chiral by isotopic substitution, which is a challenging case for typical quantum mechanical calculations. 

The OR or ORD show changes with respect to temperature that are not well explained by changes in Boltzmann averaging. This would certainly include rigid molecules. 

The ORD exhibits a bisignate nonresonant feature that cannot be explained with the intensity of low lying transitions. 

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In order to advance the usefulness of theoretical calculations in broader applications, the computations should be carried out for a system that describes experimental conditions as accurately as possible. To do this, consider the following topics for a description of a system beyond using a single static structure at 0 K conformational averaging of static gas phase structures (this has been partially addressed already in Sect. 3), solvent effects on static structures, zero-point and finite temperature vibrational averaging, and molecular dynamics (MD) or Monte-Carlo (MC) sampling without and with solvation. 

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