Quantum dynamics of N-methylacetamide studied by the vibrational configuration interaction method

TL;DR

This study investigates the vibrational energy transfer in N-methylacetamide's amide I mode using quantum dynamics and vibrational configuration interaction, revealing key energy flow pathways influenced by anharmonic couplings.

Contribution

It introduces a detailed quantum dynamical analysis of vibrational energy transfer in NMA using a vibrational configuration interaction approach with a constructed quartic force field.

Findings

Identified dominant energy transfer pathways in NMA.

Showed the sensitivity of energy flow to anharmonic couplings.

Validated the force field against experimental and theoretical data.

Abstract

Vibrational energy transfer of the amide I mode of N-methylacetamide (NMA) is studied theoretically using the vibrational configuration interaction method. A quartic force field of NMA is constructed at the B3LYP/6-31G+(d) level of theory and its accuarcy is checked by comparing the resulting anharmonic frequencies with available theoretical and experimental values. Quantum dynamics calculations for the amide I mode excitation clarify the dominant energy transfer pathways, which sensitively depend on the anharmonic couplings among vibrational modes. A ratio of the anharmonic coupling to the frequency mismatch is employed to predict and interpret the dominant energy flow pathways.