Computational study of molecules with high intrinsic hyperpolarizabilities

Area of Science:

• Computational Chemistry
• Molecular Design
• Nonlinear Optics

Background:

• Chromophores with high intrinsic hyperpolarizability are crucial for nonlinear optical applications.
• Aromatic moieties and conjugated bridges are key structural features for modulating electronic properties.

Purpose of the Study:

• To computationally investigate chromophores with enhanced intrinsic hyperpolarizability.
• To validate computational methods against experimental hyperpolarizability data.
• To identify optimal computational schemes for predicting molecular hyperpolarizability.

Main Methods:

• Semiempirical, Density Functional Theory (DFT), and Time-Dependent DFT (TDDFT) calculations were employed.
• Exploration of various calculation schemes, including long-range Hartree-Fock exchange corrections and solvent effects.
• Analysis using a two-level model to interpret hyperpolarizability trends.

Main Results:

• Computational results successfully reproduced experimental trends for first hyperpolarizability.
• DFT calculations incorporating long-range corrections and solvent effects showed the best agreement.
• Long-range corrections were particularly vital for azobenzene derivatives, preventing overestimation of hyperpolarizability.

Conclusions:

• The study validates computational approaches for designing chromophores with tailored hyperpolarizability.
• Optimized DFT methods provide reliable predictions for molecular hyperpolarizability.
• The two-level model offers a useful framework for understanding structure-property relationships in these molecules.