Quantum chemistry of macromolecules and solids

Area of Science:

• Computational chemistry
• Materials science
• Solid-state physics

Background:

• Accurate electronic structure calculations are crucial for understanding material properties.
• Macromolecules and nonmetallic solids present unique computational challenges.
• Existing methods often struggle with large, complex systems.

Purpose of the Study:

• To review two classes of electronic structure methods applicable to macromolecules and nonmetallic solids.
• To highlight their use in studying hydrocarbon polymers and organic molecular crystals.
• To analyze fundamental concepts like interaction decay, size extensivity, and periodicity.

Main Methods:

• Crystalline orbital (CO) theory for periodic extended systems.
• Localized-orbital, embedding-field approach for periodic or nonperiodic systems.
• Implementation of rigorous electron-correlation theories (coupled-cluster, perturbation theories) and density-functional approximations.

Main Results:

• Both methods can compute ground-state energies, equilibrium structures, and phonons.
• Excitons and quasiparticle energy bands are accessible (CO theory).
• Applications demonstrated for hydrocarbon polymers and organic molecular crystals.

Conclusions:

• The two reviewed approaches offer robust frameworks for electronic structure studies.
• Key concepts like interaction decay, size extensivity, and periodicity are vital for these theories.
• These methods provide accurate predictions for diverse macromolecular and solid-state systems.