Nonlocal STM Manipulation of Chlorobenzene on Si(111)‑7
× 7: Potentials, Kinetics, and First-Principles Molecular Dynamics
Calculations for Open Systems
posted on 2021-05-26, 14:46authored byTina Gaebel, Daniel Bein, Daniel Mathauer, Manuel Utecht, Richard Palmer, Tillmann Klamroth
We
use quantum chemical cluster models together with constrained
density functional theory (DFT) and ab initio molecular dynamics (AIMD)
for open system to simulate and rationalize nonlocal scanning tunneling
microscope (STM) manipulation experiments for chlorobenzene (PhCl)
on a Si(111)-7 × 7 surface. We consider three different processes,
namely, the electron-induced dissociation of the carbon–chlorine
bond for physisorbed PhCl molecules at low temperatures and the electron-
or hole-induced desorption of chemisorbed PhCl at 300 K. All processes
can be induced nonlocally, i.e., up to several nanometers (nm) away
from the injection site, in STM experiments. We rationalize and explain
the experimental findings regarding the STM-induced dissociation using
constrained DFT. The coupling of STM-induced ion resonances to nuclear
degrees of freedom is simulated with AIMD using the Gadzuk averaging
approach for open systems. From this data, we predict a 4 fs lifetime
for the cationic resonance. For the anion model, desorption could
not be observed. In addition, the same cluster models are used for
transition-state theory calculations, which are compared to and validated
against time-lapse STM experiments.