Structural transitions of organic polymorphs on metal surfaces

Activity: Talk or presentationPoster presentationScience to science

Description

Organic molecules can arrange in various polymorphs on surfaces, which can be already determined with an in-house program named SAMPLE[1]. Knowing the corresponding physical properties of the polymorphs allows to computationally design novel materials with superior properties. However, to be able to suggest a route on how to realize these materials, also knowledge about how the different polymorphs transform into each other is required. In particular, the following questions have to be answered beforehand: How stable single polymorphs are under specific conditions? Under which mechanisms phase transitions occur? Is there a sequence of process parameters that allows to kinetically stabilize a specific target polymorph? The key to answer these questions is to estimate lifetimes and transitions rates of polymorphs as function of environmental conditions. In practice, the main ingredients for the lifetime determination are the electronic energy barriers between neighboring polymorphs, which demands exploring the multidimensional potential energy surface. The harmonic approximation, Nudged Elastic Band method and the Dimer Method are tools, which enable a more or less sophisticated computation of energy barriers.

[1] L. Hörmann et al., Comput. Phys. Commun. 244, 143-155 (2019)
Period20 Sep 2020
Event titleAdvanced Materials Day 2020
Event typeConference
LocationVirtuell, Austria