An efficient and stable hybrid extended Lagrangian/self-consistent field scheme for solving classical mutual...

Area of Science:

• Computational Chemistry
• Molecular Dynamics
• Quantum Chemistry

Background:

• Classical polarization calculations using self-consistent field (SCF) methods can suffer from numerical instabilities.
• These instabilities, particularly in mutual induction calculations, lead to increased SCF cycles and poor energy conservation.
• Existing methods struggle to accurately and efficiently model electronic degrees of freedom in molecular dynamics.

Purpose of the Study:

• To adapt and improve the extended Lagrangian self-consistent field (EL/SCF) approach for classical polarization.
• To address numerical instabilities encountered in mutual induction calculations.
• To develop a more stable and efficient method for classical polarization in molecular dynamics.

Main Methods:

• Adapted a hybrid extended Lagrangian self-consistent field (EL/SCF) approach.
• Introduced auxiliary induced dipole variables with a time-reversible velocity Verlet scheme.
• Implemented a thermostating scheme (Berendsen, Nose-Hoover) applied to auxiliary dipole velocities to mitigate numerical instability.
• Utilized the AMOEBA14 water model for simulations.

Main Results:

• The inertial EL/SCF (iEL/SCF) method effectively suppresses numerical instabilities in classical polarization.
• iEL/SCF demonstrates superior energy conservation compared to standard SCF approaches.
• The new method achieves accurate reproduction of polarization model properties with fewer SCF cycles.
• Stable simulations were performed in both NVT and NVE ensembles.

Conclusions:

• The inertial EL/SCF (iEL/SCF) method is a significant improvement for classical mutual induction calculations.
• This approach offers enhanced stability and efficiency in molecular dynamics simulations.
• The iEL/SCF method shows potential for application in ab initio molecular dynamics.