Structural, electronic, and optical properties of a prototype columnar discotic liquid crystal

Area of Science:

• Materials Science
• Computational Chemistry
• Condensed Matter Physics

Background:

• Columnar discotic liquid crystals exhibit unique self-assembly properties.
• Hexakis-n-alkyloxy-triphenylenes (HATn) are a key class of discotic mesogens.
• Understanding molecular properties is crucial for designing advanced materials.

Purpose of the Study:

• To calculate structural, electronic, and optical properties of an infinite column of hexakis-hydroxy-triphenylene (HAT0) molecules.
• To model columnar discotic liquid crystals using HAT0 as a prototype.
• To investigate the potential for electronic transport in HAT0 molecular columns.

Main Methods:

• Car-Parrinello molecular dynamics for structural optimization.
• Kohn-Sham calculations for electronic properties (orbitals, density of states).
• Quantum mechanical calculations of the transverse dielectric function and optical absorption spectra.
• ZINDO method for short columns and nonequilibrium Green's function for electronic transport.

Main Results:

• Structural optimization of the infinite HAT0 column was achieved.
• Calculated optical absorption spectra agree well with experimental data for HATn compounds.
• Electronic transport properties were estimated for a model system of HAT0 molecules between gold electrodes.

Conclusions:

• The infinite column model effectively represents columnar discotic liquid crystals.
• The calculated properties support the proposed columnar arrangement of discotic molecules.
• HAT0 molecular columns show promise for electronic transport applications.