Information and complexity measures in molecular reactivity studies

Area of Science:

• Theoretical Chemistry
• Quantum Chemistry
• Computational Chemistry

Background:

• Information and complexity measures are valuable tools for investigating chemical reactivity.
• Understanding atomic and group transferability is crucial for analyzing molecular properties.
• Different representations (spinor density vs. shape function) can impact the reliability of these measures.

Purpose of the Study:

• To analyze information and complexity measures in spin-position and position spaces using density and shape representations.
• To evaluate the transferability and additivity of atoms and functional groups as checkpoints for chemical reactivity.
• To compare the effectiveness of spinor density versus shape function representations in information-theoretical analyses.

Main Methods:

• Utilized information-theoretical measures like Shannon entropy (SE), Fisher information (FI), and Onicescu information (OI).
• Analyzed results in both spin-position and position spaces for density and shape representations.
• Examined transferability and additivity using molecular examples like X-Y molecules, benzene derivatives, and alkanes-alkenes-alkynes.

Main Results:

• Spinor density representations accurately show atom and group transferability, unlike shape function representations which can lead to erroneous conclusions.
• The Shannon-entropy-Fisher-information (S-I) plane provides richer insights into molecular patterns and similarity compared to other information-theoretical measure planes.
• High-accuracy linear relationships were observed between kinetic energy and Fisher information/Onicescu information, and between atomization total energy and atomization entropy.

Conclusions:

• Spinor density is a more reliable representation than shape function for information-theoretical analysis of chemical reactivity and transferability.
• Information-theoretical measures, particularly on the S-I plane, offer valuable insights into molecular organization and similarity.
• While group electronic energy transferability is lacking, the study advances the understanding and generalization of molecular complexities and their relation to chemical reactivity.