Density Embedding Method for Nanoscale Molecule–Metal Interfaces

Abstract

In this work, we extend the applicability of standard Kohn–Sham DFT (KS-DFT) to model realistically sized molecule–metal interfaces where the metal slabs venture into the tens of nanometers in size. Employing state-of-the-art noninteracting kinetic energy functionals, we describe metallic subsystems with orbital-free DFT and combine their electronic structure with molecular subsystems computed at the KS-DFT level resulting in a multiscale subsystem DFT method. The method reproduces within a few millielectronvolts the binding energy difference of water and carbon dioxide molecules adsorbed on the top and hollow sites of an Al(111) surface compared to KS-DFT of the combined supersystem. It is also robust for Born–Oppenheimer molecular dynamics simulations. Very large system sizes are approached with standard computing resources thanks to a parallelization scheme that avoids accumulation of memory at the gather–scatter stage. The results as presented are encouraging and open the door to ab initio simulations of realistically sized, mesoscopic molecule–metal interfaces.

Orbital-Free Density Functional Theory: An Attractive Electronic Structure Method for Large-Scale First-Principles Simulations

“…OFDFT can play an even greater role in sDFT simulations. For example, the combination, in a single subsystem DFT simulation, of conventional KSDFT solvers for molecular subsystems and OFDFT solvers for metallic surfaces recently was reported by Shao et al In that work, the binding energies of molecules at Al(111) surfaces were reported to be within a few meV of the conventional KSDFT values. Additionally, thanks to the advantageous computational scaling of OFDFT, the hybrid OFDFT/KSDFT subsystem DFT method yielded the electronic structure of large water/Al(111) interfaces in record wall times.…”

“…For more details on high-efficiency implementations, parallelization schemes, and other details of sDFT implementations, we refer the interested reader to refs − , , , , and − .…”

Subsystem density‐functional theory (update)

“…A similar strategy was applied for water and benzene on molybdenum sulfide surfaces 182,183,192 . To tackle even larger systems, sDFT can be further combined with orbital‐free DFT for metallic subsystems, as was demonstrated for water and $$$ {\mathrm{CO}}_2 $$$ on aluminum surfaces 193 …”

“…182,183,192 To tackle even larger systems, sDFT can be further combined with orbital-free DFT for metallic subsystems, as was demonstrated for water and CO 2 on aluminum surfaces. 193 Also molecular implementations of sDFT can be extended toward the treatment of condensed-phase systems. Höfener and coworkers 194 have developed a scheme that imposes periodic boundary conditions in one dimension.…”

Adaptive Subsystem Density Functional Theory

“…A major benefit of using comm_region is that it avoids gathering global data (from the large simulation grid) on a single CPU which would be unfeasible for large systems. See ref for additional details.…”