Accelerating rare events while overcoming the low-barrier problem using a temperature program.

Area of Science:

• Materials Science
• Computational Chemistry
• Statistical Mechanics

Background:

• Molecular dynamics (MD) simulations struggle with rare events due to vast timescales.
• Materials often exhibit complex energy landscapes with multiple energy basins (superbasins).
• Transitions between superbasins involve high-energy barriers, making them rare in standard MD.

Purpose of the Study:

• To introduce a novel hierarchical coarse-grained simulation technique, temperature programmed molecular dynamics (TPMD).
• To accelerate the simulation of rare events in materials, particularly superbasin escape events.
• To accurately capture superbasin-to-superbasin transitions at original temperatures with reduced computational cost.

Main Methods:

• Developed the temperature programmed molecular dynamics (TPMD) method.
• Employed a temperature program to alter MD simulation temperature, facilitating access to low-barrier moves.
• Implemented a coarse-graining strategy by ignoring transitions within detected superbasins.
• Applied the TPMD method to study surface diffusion in the Ag/Ag(001) system.

Main Results:

• TPMD effectively overcomes the computational challenge of low-barrier transitions within superbasins.
• The method accurately reproduces superbasin-to-superbasin transitions at the original simulation temperature.
• Demonstrated the ability of TPMD to simulate processes across a wide range of timescales.
• Successfully applied to surface diffusion in Ag/Ag(001), validating its practical utility.

Conclusions:

• TPMD is an efficient technique for accelerating molecular dynamics simulations of rare events.
• The method provides accurate results for superbasin transitions with significant computational savings.
• TPMD offers a powerful approach for studying complex materials behavior and surface dynamics.