First-Principles Investigation of Excited-State Lattice Dynamics and Mechanical Properties in Diamond

Area of Science:

• Materials Science
• Solid-State Physics
• Computational Chemistry

Background:

• Understanding excited-state properties of diamond is vital for its use in optoelectronics, quantum technologies, and catalysis.
• Theoretical insights into diamond's electronic structure and surface properties are essential for advanced applications.

Purpose of the Study:

• To investigate the excited-state properties of diamond using computational methods.
• To analyze the impact of electron excitation on diamond's structural, mechanical, and electronic characteristics.

Main Methods:

• Density Functional Theory (DFT) with the fixed electron occupation method.
• Generalized Gradient Approximation (GGA) for simulating electron transfer from Highest Occupied Crystal Orbital (HOCO) to Lowest Unoccupied Crystal Orbital (LUCO).

Main Results:

• Diamond transitions from cubic to tetragonal structure with increasing electron excitation.
• Bandgap decreases, Young's and shear moduli reduce, while bulk modulus remains constant.
• Phonon dispersion curves show reduced degeneracy and decreased crystal symmetry upon excitation.

Conclusions:

• Electronic excitation significantly alters diamond's mechanical stability and crystal structure.
• This research provides theoretical insights into tuning diamond's performance under extreme conditions.