Next Generation Extended Lagrangian First Principles Molecular Dynamics

  • Online Seminar
  • Date: May 14, 2020
  • Time: 16:00
  • Speaker: Dr. Anders M.N. Niklasson
  • Los Alamos National Laboratory, Los Alamos, NM, USA
  • Location: Join the webinar: https://us02web.zoom.us/j/89740304941?pwd=YnN5eU84VkxtZ0YwU1p0K3JMeEJEdz09 | Webinar ID: 897 4030 4941 | Password: FAIRDI2020
  • Host: Christian Carbogno
  • Contact: christian.carbogno@fhi-berlin.mpg.de
Next Generation Extended Lagrangian First Principles Molecular Dynamics
Quantum-based Born-Oppenheimer molecular dynamics (QMD) simulations, where the interatomic forces are calculated on the fly from a relaxed quantum-mechanical description of the electronic structure in each time step, is often considered the gold standard for molecular dynamics simulations.

It represents a predictive and almost universal tool to analyze and tailor material systems in chemistry, materials science and molecular biology. Unfortunately, current QMD methods are often painfully slow or have stability problems with a systematic drift in the total energy. QMD simulations are therefore limited to small system and short simulation times. In this presentation I will review a new efficient framework that overcomes several of the previous problems and shortcomings in QMD simulations. The framework is based on an extended Lagrangian formulation in the spirit of Car-Parrinello molecular dynamics and avoids the costly overhead in an iterative ground state optimization required prior to the force evaluations in a regular direct Born-Oppenheimer simulations. However, the extended Lagrangian and the equations of motion are different from Car-Parrinello molecular dynamics. In particular, the integration time step is not limited by a fictitious electron-mass parameter and the constant of motion is in practice identical to the total energy of a regular direct Born-Oppenheimer simulation. The new framework is also applicable to highly challenging problems, including reactive chemical systems with a closing electronic gap, where regular direct Born-Oppenheimer molecular dynamics simulations have particular problems with the SCF convergence.

Ref: A.M.N. Niklasson, https://arxiv.org/abs/2003.09050;

A.M.N. Niklasson, J. Chem. Phys. 152, 104103 (2020); doi: 10.1063/1.5143270

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