Extended Lagrangian Born-Oppenheimer molecular dynamics with dissipation.
Stability and dissipation in the propagation of the electronic degrees of freedom in time-reversible extended Lagrangian Born-Oppenheimer molecular dynamics [Niklasson et al., Phys. Rev. Lett. 97, 123001 (2006); Phys. Rev. Lett. 100, 123004 (2008)] are analyzed. Because of the time-reversible propagation the dynamics of the extended electronic degrees of freedom is lossless with no dissipation of numerical errors. For long simulation times under "noisy" conditions, numerical errors may therefore accumulate to large fluctuations. We solve this problem by including a dissipative external electronic force that removes noise while keeping the energy stable. The approach corresponds to a Langevin-like dynamics for the electronic degrees of freedom with internal numerical error fluctuations and external, approximately energy conserving, dissipative forces. By tuning the dissipation to balance the numerical fluctuations the external perturbation can be kept to a minimum.
Niklasson
Anders M N
AM
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. amn@lanl.gov
Steneteg
Peter
P
Odell
Anders
A
Bock
Nicolas
N
Challacombe
Matt
M
Tymczak
C J
CJ
Holmström
Erik
E
Zheng
Guishan
G
Weber
Valery
V