Size-Reduction of Phonon Band Calculation for Coarse-Grained Molecular Crystals Using "Independent Stiffness...

Area of Science:

• Solid State Physics
• Computational Materials Science
• Crystallography

Background:

• Conventional methods for calculating phonon band diagrams of molecular crystals use atoms as the basic vibrational unit.
• This atomic-level approach leads to high computational costs and complicates vibrational mode analysis for complex molecular structures.

Purpose of the Study:

• To introduce a novel computational scheme for efficient phonon band diagram calculations in molecular crystals.
• To reduce computational expense and improve the interpretability of vibrational modes by treating molecules as fundamental units.

Main Methods:

• A coarse-graining (CG) scheme was employed, representing molecules as the primary vibrational units.
• The independent stiffness approximation (ISA) was developed to construct approximate dynamical matrices from smaller partial matrices.
• The CG scheme was integrated with ISA for lattice calculations.

Main Results:

• The combined CG and ISA approach was applied to calculate and analyze the phonon band diagram of β-phase dichlorobenzene.
• The study validated the accuracy and reliability of the proposed computational method.

Conclusions:

• The proposed CG and ISA method offers a more efficient and intuitive approach for calculating phonon band diagrams of molecular crystals.
• This method has the potential to significantly advance the study of vibrational properties in molecular materials.