title: Geometric integration in Born-Oppenheimer molecular dynamics.
abstract: Geometric integration schemes for extended Lagrangian self-consistent Born-Oppenheimer molecular dynamics, including a weak dissipation to remove numerical noise, are developed and analyzed. The extended Lagrangian framework enables the geometric integration of both the nuclear and electronic degrees of freedom. This provides highly efficient simulations that are stable and energy conserving even under incomplete and approximate self-consistent field (SCF) convergence. We investigate three different geometric integration schemes: (1) regular time reversible Verlet, (2) second order optimal symplectic, and (3) third order optimal symplectic. We look at energy conservation, accuracy, and stability as a function of dissipation, integration time step, and SCF convergence. We find that the inclusion of dissipation in the symplectic integration methods gives an efficient damping of numerical noise or perturbations that otherwise may accumulate from finite arithmetics in a perfect reversible dynamics.
authors.affiliation: Swedish Defence Research Agency (FOI), Defence and Security Systems and Technology Division, SE-147 25 Tumba, Sweden. aodell@kth.se
authors.forename: Anders
authors.initials: A
authors.lastname: Odell
authors.forename: Anna
authors.initials: A
authors.lastname: Delin
authors.forename: Börje
authors.initials: B
authors.lastname: Johansson
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Cawkwell
authors.forename: Anders M N
authors.initials: AM
authors.lastname: Niklasson
mesh_terms: D008697:Methane / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory
chemical_list: D008697:Methane