Frictional effects near a metal surface

Area of Science:

• Physical Chemistry
• Surface Science
• Theoretical Chemistry

Background:

• Classical master equations (CME) model molecular dynamics at metal surfaces.
• Understanding nonadiabatic dynamics and electron transfer (ET) is crucial.

Purpose of the Study:

• To reduce CME to a Fokker-Planck equation for molecule-metal systems.
• To investigate the role of electronic friction in electron transfer.
• To analyze the fluctuation-dissipation theorem in this context.

Main Methods:

• Derivation of a Fokker-Planck equation from a CME under strong molecule-metal coupling.
• Analysis of electronic friction and random forces for a single metal substrate.
• Investigation of electron transfer rates as a function of frictional damping.

Main Results:

• The CME reduces to a Fokker-Planck equation with explicit electronic friction.
• Electronic friction and random forces satisfy the fluctuation-dissipation theorem.
• Electron transfer rates exhibit a turnover effect with increasing frictional damping.

Conclusions:

• The Fokker-Planck description is valid for strong molecule-metal couplings.
• Electronic friction significantly influences electron transfer dynamics.
• The turnover effect in ET rates provides insights into energy dissipation mechanisms.