Towards the crystal structure of thymine: An intermolecular force field development and parallel global cluster...

Area of Science:

• Computational chemistry
• Molecular modeling
• Crystallography

Background:

• Understanding molecular interactions is crucial for predicting material properties.
• Thymine dimers are fundamental units in DNA and crystal formation.

Purpose of the Study:

• To develop a novel *ab initio* potential for thymine dimers.
• To investigate the self-assembly of thymine clusters.
• To correlate dimer interactions with crystal structure formation.

Main Methods:

• Density Functional Theory (DFT) and Symmetry-Adapted Perturbation Theory (SAPT) were combined to create a new potential.
• High-level coupled cluster with singles, doubles, and triples (CCSD(T)) calculations were used for validation.
• Global cluster optimizations were performed for clusters up to 50 molecules.

Main Results:

• The DFT-SAPT potential accurately reproduced reference CCSD(T) calculations for hydrogen-bonded and stacked thymine dimers.
• Cluster optimizations revealed that structures formed are precursors to the thymine crystal lattice.
• The study demonstrates a strong link between dimer-level interactions and macroscopic crystal structures.

Conclusions:

• The developed DFT-SAPT potential is a reliable tool for studying thymine dimer interactions.
• Dimer potentials are essential for understanding and predicting the formation of crystal structures.
• This work provides a foundation for further investigations into molecular self-assembly and crystal engineering.