ao8b00316_si_001.pdf (1 MB)
Physics behind the Barrier to Internal Rotation of an Acetyl Chloride Molecule: A Combined Approach from Density Functional Theory, Car–Parrinello Molecular Dynamics, and Time-Resolved Wavelet Transform Theory
journal contribution
posted on 2018-06-22, 14:48 authored by Bipan Dutta, Biplab Bhattacharjee, Joydeep ChowdhuryThe physics behind the barriers to
internal rotation of acetyl
chloride (AC) molecule has been reported. The AC molecule closely
resembles the molecular structure of acetaldehyde; the only subtle
difference is the presence of a heavy chlorine atom in place of the
hydrogen atom of the aldehyde group for the latter. This paper aims
to study the effect of substitution of the heavy chlorine atom on
the barrier energetics of the AC molecule. The reason behind the barrier
for the AC molecule has been estimated for the first time from the
unified approach using barrier energetics, natural bond orbital, nuclear
virial, and relaxation analyses using density functional theory, Car–Parrinello
molecular dynamics, and wavelet transform theory. Complete analyses
reveal the concomitant relaxations of both the in-plane Cmethyl–C1 and Cmethyl–H4 bonds toward understanding the origin of the barrier due to internal
rotation for the AC molecule. The large negative value of “V6” further suggests that both the abovementioned
degrees of freedom are coupled with the −CH3 torsional
vibration of the molecule. The coupling matrix (H12) element has also been estimated. Time-resolved band
stretching frequencies of Cmethyl–C1 and
C1–Cl3 bonds of the AC molecule, as obtained
from wavelet transformation analysis, primarily preclude the possibility
of coupling between the C1–Cl3 bond and
the torsional motion associated with the methyl group of the molecule.