EMPIRE: a highly parallel semiempirical molecular orbital program: 3: Born-Oppenheimer molecular dynamics

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Semiempirical molecular orbital methods offer a balance between accuracy and computational cost.
• Molecular dynamics (MD) simulations are crucial for understanding molecular behavior over time.
• Previous limitations in computational power restricted the scale and duration of quantum mechanical MD simulations.

Purpose of the Study:

• To implement direct NDDO-based Born-Oppenheimer molecular dynamics (MD) within the EMPIRE program.
• To enable fully quantum mechanical MD simulations on unprecedented time and length scales.
• To provide a versatile platform for simulating condensed-phase systems and complex molecular structures.

Main Methods:

• Direct NDDO-based Born-Oppenheimer molecular dynamics (MD) implementation.
• Massively parallel computation of self-consistent wavefunctions and gradients.
• Support for NVE and NVT ensembles with deterministic (Berendsen) or stochastic (Langevin) thermostats.
• Periodic boundary conditions for condensed-phase simulations.

Main Results:

• Successful implementation of direct NDDO-based Born-Oppenheimer MD in EMPIRE.
• Demonstration of simulations on unprecedented time and length scales.
• Exemplary applications including molecular reorganization, endohedral fullerene dynamics, and nanoparticle vibrational spectra.

Conclusions:

• The developed method significantly advances the capabilities of quantum mechanical MD simulations.
• Enables the study of complex systems previously inaccessible due to computational limitations.
• Opens new avenues for research in areas like materials science and physical chemistry.