How much does surface polymorphism influence the work function of organic/metal interfaces?

Molecules adsorbing on metal surfaces form a variety of different surface polymorphs. How strongly this polymorphism affects interface properties is priori unknown. In work we investigate how the influences functions for various organic/metal interfaces. To evaluate whole bandwidth possible polymorphs, perform full theoretical structure search, probing millions polymorph candidates. All these candidates might be observed in reality, either by kinetic trapping or thermodynamic occupation. Employing first-principles calculations and machine learning predict analyze function changes those three physically distinct model systems: weakly interacting naphthalene Cu(111), anthraquinone Ag(111), tetracyanoethylene, which undergoes reorientation from lying to standing polymorphs Cu(111) surface. These thorough investigations indicate that flat-lying molecules can lead differences few hundred meV. If also reorientate, increase change several eV. We further show spread decreases when working equilibrium, but thermally occupied phases still an intrinsic uncertainty at elevated temperatures.