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O: Fachverband Oberflächenphysik

O 28: Electronic Structure Theory: General I

O 28.2: Vortrag

Dienstag, 13. März 2018, 10:45–11:00, MA 141

An adaptive approach to solid-state QM/MM embedding — •Jakob Filser, Karsten Reuter, and Harald Oberhofer — Technische Universität München

QM/MM embedding in crystals [1,2] is a powerful approach to the simulation of non-periodic phenomena such as defects, as it eliminates issues like spurious self-interaction that are present in periodic boundary condition (PBC) supercell calculations. On the other hand, the performance of an embedding model depends crucially on the treatment of the QM/MM boundary and the long-range electrostatics in the MM region. Static setups that employ fixed effective core potentials (ECPs) to prevent charge leakage at the QM/MM boundary and fixed formal charges in the MM region are a common approach as both ECPs and formal charges are readily available [2]. However, such setups do not ensure correct reproduction of the electrostatic potential inside the QM region. We revisit this from an adaptive perspective, aiming to reproduce properties of reference density-functional theory PBC calculations in embedded defect-free supercells. Instead of fixed ECPs we optimize pseudo-potentials with an evolutionary algorithm to reproduce the charge distribution and energetics inside the QM region, providing a proof of concept that ECPs are indeed not the best choice for this purpose. For the MM region we propose a procedure to adapt the point charges to recover the long-range electrostatic potential.

[1] P. Sherwood et al., J. Mol. Struct. - Theochem. 623, 1 (2003).

[2] D. Berger et al., J. Chem. Phys. 141, 024105 (2014).