A Universal Force Field for Materials, Periodic GFN-FF: Implementation and Examination.

Area of Science:

• Computational chemistry
• Materials science
• Solid-state physics

Background:

• The GFN-FF method is a popular molecular mechanics force field.
• Handling periodic boundary conditions is crucial for simulating bulk materials.
• Existing methods may struggle with accurate charge and dispersion calculations in periodic systems.

Purpose of the Study:

• To adapt the GFN-FF method for periodic boundary conditions (pGFN-FF).
• To introduce improvements for calculating topological charges and three-body dispersion.
• To validate the performance of the modified pGFN-FF scheme across various material dimensionalities.

Main Methods:

• Implementation of neighbor lists and charge sums for handling 1D, 2D, and 3D periodic systems.
• Numerical integration over the Brillouin zone for periodic π bond order calculations.
• Inclusion of a screened Coulomb term for topological charges and short-range damping for three-body dispersion.
• Formulation of analytic second derivatives with respect to Cartesian and strain variables.

Main Results:

• The pGFN-FF scheme successfully handles various dimensionalities (1D, 2D, 3D).
• Improvements in charge calculations lead to more physical results and avoid pathological cases.
• Inclusion of damping prevents structural collapse in some systems.
• The modified scheme shows good performance when applied to a diverse range of materials.

Conclusions:

• The developed pGFN-FF is a versatile tool for simulating periodic materials.
• The proposed improvements enhance the accuracy and robustness of the GFN-FF method for periodic systems.
• The universal model demonstrates broad applicability in materials research.