LCAO Electronic Structure of Nucleic Acid Bases and Other Heterocycles and Transfer Integrals in B-DNA, Including...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Modeling

Background:

• Accurate molecular electronic structure calculations are crucial for understanding chemical and biological processes.
• Existing methods like the Hückel approach have limitations in describing complex molecular geometries, such as DNA structural variability.

Purpose of the Study:

• To develop and validate an improved Linear Combination of Atomic Orbitals (LCAO) method for calculating electronic structures of nucleic acid bases and heterocycles.
• To investigate the impact of structural deformations on electronic properties and charge transport in DNA.

Main Methods:

• Employed a novel parameterization for on-site energies in the LCAO method.
• Utilized Slater-Koster two-center interaction transfer integrals for non-diagonal matrix elements.
• Incorporated all valence orbitals (2s, 2p, 1s) to handle non-planar geometries.
• Validated predictions against high-level quantum chemistry methods (IP-EOMCCSD, CR-EOMCCSD(T)) and experimental data.
• Calculated transfer integrals for a Tight-Binding (TB) model of DNA charge transport.

Main Results:

• The novel LCAO parameterization accurately predicts ionization and excitation energies for heterocycles.
• The method successfully accounts for electronic structure changes due to non-planar geometries and DNA structural variability.
• Calculated transfer integrals provide insights into charge transfer and transport along B-DNA, including deformed structures.

Conclusions:

• The enhanced LCAO method offers a robust approach for studying the electronic properties of complex molecules and biomolecules.
• This method enables the investigation of DNA charge transport influenced by structural dynamics, advancing our understanding of DNA function and mutation.