Periodic density functional theory calculations for 3-dimensional polyacetylene with empirical dispersion terms

Area of Science:

• Computational Chemistry
• Materials Science
• Polymer Physics

Background:

• Three-dimensional (3D) trans-polyacetylene (t-PA) is a conjugated polymer with potential applications in electronics.
• Accurate theoretical modeling of 3D t-PA is challenging due to complex interchain interactions.

Purpose of the Study:

• To perform periodic density functional theory calculations for 3D t-PA fibers.
• To investigate the role of empirical dispersion corrections in modeling 3D t-PA.
• To explain observed X-ray diffraction (XRD) intensities.

Main Methods:

• Periodic B3LYP density functional theory calculations.
• Inclusion of empirical dispersion corrections (Grimme's method) with re-scaling (B3LYP+D*).
• Utilized the CRYSTAL06 computational chemistry software.

Main Results:

• Dispersion corrections are critical for accurate unit cell parameters of 3D t-PA.
• The P2(1)/n structure was identified as a transition state for interchain motion.
• Calculated energies align with observed XRD intensities, suggesting a new explanation.

Conclusions:

• The B3LYP+D* method provides a reliable approach for studying 3D t-PA.
• The findings offer a new interpretation for experimental XRD data.
• These calculations serve as a benchmark for more advanced theoretical treatments.