London Dispersion Effects on the Structure and Properties of Nonlinear Optical BiB₃O₆ Crystal

Area of Science:

• Materials Science
• Solid State Physics
• Crystallography

Background:

• α-BiB3O6 (BiBO) is a significant nonlinear optical material with potential in quantum technology.
• Previous theoretical calculations of BiBO's physical properties yielded inaccurate results, hindering its application.
• The influence of London dispersion forces on BiBO's structure and properties was previously overlooked.

Purpose of the Study:

• To accurately model the crystal structure of α-BiB3O6 (BiBO) by incorporating London dispersion (LD) corrections.
• To precisely calculate key material property tensors for BiBO, including dielectric, elastic, piezoelectric, and electro-optic coefficients.
• To provide reliable theoretical data for designing advanced optical and electro-optic devices utilizing BiBO.

Main Methods:

• Application of a modified post-Density Functional Theory (DFT) London dispersion (LD) correction using linear combination of atomic orbitals (LCAO) and B3LYP functional.
• Theoretical optimization of the BiBO crystal structure to match experimental data.
• Calculation of various material property tensors, including static and THz dielectric constants, elastic, elasto-optic, piezoelectric, and electro-optic coefficients.

Main Results:

• The LD-corrected DFT calculations accurately reproduced the experimental structure of BiBO, correcting overestimations in previous models.
• Precise theoretical values were obtained for dielectric constants (static and THz), elastic, elasto-optic, and piezoelectric constants (d22=40 pC/N).
• First-time theoretical calculations of THz refractive indices and clamped-ion electro-optic coefficients (r11=-4.17 pm/V, r22=-2.61 pm/V) were achieved, revealing their origin from piezoelectric effects.

Conclusions:

• Incorporating London dispersion corrections is essential for accurate theoretical modeling of BiBO's structure and properties.
• The precise theoretical data provided will aid in the design of high-speed electro-optic modulators and advanced acousto-optic devices.
• BiBO exhibits exceptional piezoelectric and electro-optic properties, making it a promising material for next-generation optical and quantum technologies.