Geometry optimization of periodic systems using internal coordinates

Area of Science:

• Computational materials science
• Solid-state chemistry
• Crystallography

Background:

• Structural optimization is crucial for understanding material properties.
• Existing methods for periodic systems often lack comprehensive internal coordinate handling.
• Accurate representation of lattice parameters and atomic positions is essential for reliable simulations.

Purpose of the Study:

• To develop and present a novel algorithm for structural optimization of periodic systems.
• To incorporate lattice internal coordinates alongside chemical internal coordinates.
• To improve the accuracy and efficiency of structural optimization for crystalline materials.

Main Methods:

• An algorithm utilizing a generalized Wilson B-matrix for coordinate transformations.
• Inclusion of explicit dependence of lattice parameters on atomic positions.
• Application of ab initio density functional theory (DFT) with projector-augmented wave (PAW) formalism for energies and forces.

Main Results:

• Demonstrated successful structural optimization for layered and microporous materials (gibbsite, chabazite) and molecular crystals (urea).
• The generalized B-matrix accurately captures the coupling between atomic positions and lattice parameters.
• The method performs effectively even with constrained optimizations.

Conclusions:

• The proposed algorithm provides a robust framework for structural optimization of periodic systems in internal coordinates.
• This approach offers enhanced accuracy by fully accounting for lattice parameter dependencies.
• The method is applicable to a wide range of crystalline materials and computational settings.