A numerical comparison between Ehrenfest dynamics and purification of the density matrix method for Born-Oppenheimer dynamics
(English)Manuscript (preprint) (Other academic)
In this paper we numerically compare the computational efficiency between the Born-Oppenheimer dynamics based on purification of the density matrix, and the Ehrenfest molecular dynamics. In particular we study a set of problems when the ground state and excited state eigenvalues of the electronic energy surfaces come close to each other creating the so called near avoided conical intersections. The numerical results based on a simple model problem show that the Born-Oppenheimer molecular dynamics based on purification of the density matrix performs better compared to the Ehrenfest molecular dynamics. For instance, the Ehrenfest dynamics needs to resolve all spectral gaps, also between occupied states, whereas only the spectral gap between the highest occupied and lowest unoccupiedmolecular orbitals is required to be resolved for the Born-Oppenheimer molecular dynamics based on the purification of the density matrix method.
molecular dynamics, Ehrenfest dynamics, Born-Oppenheimer dynamics
Research subject Applied and Computational Mathematics
IdentifiersURN: urn:nbn:se:kth:diva-195097OAI: oai:DiVA.org:kth-195097DiVA: diva2:1044047
FunderSwedish e‐Science Research Center
QC 201611032016-11-012016-11-012016-11-03Bibliographically approved