Molecular Hyperdynamics Coupled with the Nonorthogonal Tight-Binding Approach: Implementation and Validation.

Area of Science:

• Computational physics
• Materials science
• Chemical physics

Background:

• Conventional molecular dynamics (MD) struggles with simulating long timescales (e.g., >1 second).
• Studying thermal-induced defects in atomic systems requires long-timescale simulations, especially at low temperatures.
• Existing methods often require prior knowledge of the system's potential energy landscape.

Purpose of the Study:

• Introduce the molecular hyperdynamics algorithm and its implementation with the nonorthogonal tight-binding model (NTBM).
• Enable simulations of atomic systems over timescales exceeding 1 second.
• Investigate thermal-induced defects in atomic systems without needing pre-existing potential landscape information.

Main Methods:

• Developed a multiscale molecular hyperdynamics algorithm.
• Implemented the algorithm with the nonorthogonal tight-binding model (NTBM) and associated software.
• Automatically derived optimal interatomic potential modifications from simulation steps.

Main Results:

• Achieved simulation timescales greater than 1 second, significantly longer than conventional MD.
• Validated the method on C60 fullerene and C60NH2, yielding results consistent with conventional MD.
• Demonstrated high performance and accuracy with acceleration coefficients exceeding 10^7.
• Accurately evaluated physical time using the average time between potential energy fluctuations.

Conclusions:

• Molecular hyperdynamics offers a powerful approach for long-timescale simulations of atomic systems.
• The method is particularly effective for studying low-temperature thermal-induced defects in medium to large atomic systems.
• The algorithm provides enhanced performance and accuracy compared to conventional MD, with broad applicability.