Extended Lagrangian Born-Oppenheimer Molecular Dynamics with Numeric Atom-Centered Orbitals

Stable trajectories from direct Born-Oppenheimer molecular dynamics (BOMD) require very accurate forces and, as such, a tightly converged self-consistent field optimization in each time evolution step. Contrary to direct BOMD, only a single optimization step is necessary in Extended Lagrangian Born-Oppenheimer molecular dynamics (XL-BOMD) [1] prior to each force evaluation, thus greatly reducing computational cost. We discuss a new implementation of XL-BOMD in the all electron, numeric atom-centered orbital code FHI-aims [2]. The extended electronic system is represented by the density matrix within Kohn-Sham density-functional theory. We ensure efficiency by implementing core aspects of the scheme within the Electronic Structure Infrastructure [3]. The stability of the implementation for diverse types of material critically depends on the kernel K that determines the acceleration in the integration of the extended electronic system. We address the stability and performance of different K for several types of systems (isolated molecules, metals, semiconductors).

[1] A. M. N. Niklasson, J. Chem. Theory Comput. (2020), 16(6), 3628.
[2] V. Blum et al., Comput. Phys. Commun. (2009), 180, 2175.
[3] V. Yu et al., Comput. Phys. Commun. (2020), 256, 107459.