Ab-initio methods for molecular design

Ivano Tavernelli
École Polytechnique Fédérale de Lausanne (EPFL)

The ab initio design of new compounds and materials is a very promising area of research because it offers the possibility to guide, in a rational way, the search in the chemical space.
In particular, ab-initio molecular dynamics (MD) can provide an atomistic description of the structural changes necessary to target a desired chemico-physical property in materials, while specific ab-initio electronic properties can be used as guiding forces in the chemical space for the design of molecules with tailored characteristics.
In the fist part of this contribution, I will present a systematic first-principles study of the early stages of radiation damage of graphite, a general model for closely related layered carbon nanostructures.
Nowadays, radiation treatment by high-energy electrons or ions is also viewed as a versatile tool for the design of new materials. The formation of irradiation-induced defects in graphitelike layered carbon nanostructures changes their mechanical and electronic properties and may even trigger dramatic structural changes. Knowledge of the mechanisms underlying these processes is crucial for a defect-assisted engineering of nanostructures with applications in, e.g., manufacturing of nanoelectromechanical systems.
In the second part, I will discuss some new theoretical developments for the design of novel organometallic dyes used in Graetzel-type solar cells. These are based on chemical modifications subjected to appropriate selective pressure (in the evolutionary sense) or, to deterministic forces computed within Time Dependent Density Functional Theory.

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