title: Thermostating extended Lagrangian Born-Oppenheimer molecular dynamics.
abstract: Extended Lagrangian Born-Oppenheimer molecular dynamics is developed and analyzed for applications in canonical (NVT) simulations. Three different approaches are considered: the Nosé and Andersen thermostats and Langevin dynamics. We have tested the temperature distribution under different conditions of self-consistent field (SCF) convergence and time step and compared the results to analytical predictions. We find that the simulations based on the extended Lagrangian Born-Oppenheimer framework provide accurate canonical distributions even under approximate SCF convergence, often requiring only a single diagonalization per time step, whereas regular Born-Oppenheimer formulations exhibit unphysical fluctuations unless a sufficiently high degree of convergence is reached at each time step. The thermostated extended Lagrangian framework thus offers an accurate approach to sample processes in the canonical ensemble at a fraction of the computational cost of regular Born-Oppenheimer molecular dynamics simulations.
authors.affiliation: Material Science and Technology Division, MST-8, Los Alamos National Laboratory, Los Alamos, 87545 New Mexico, USA.
authors.forename: Enrique
authors.initials: E
authors.lastname: Martínez
authors.affiliation: Theoretical Division, T-1, Los Alamos National Laboratory, Los Alamos, 87545 New Mexico, USA.
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Cawkwell
authors.affiliation: Theoretical Division, T-1, Los Alamos National Laboratory, Los Alamos, 87545 New Mexico, USA.
authors.forename: Arthur F
authors.initials: AF
authors.lastname: Voter
authors.affiliation: Theoretical Division, T-1, Los Alamos National Laboratory, Los Alamos, 87545 New Mexico, USA.
authors.forename: Anders M N
authors.initials: AM
authors.lastname: Niklasson