Chemical Dynamics Theory Group

We study structural properties (electronics, energetics, etc.) of graphene and nanographenes in the presence of atomic–size defects such as adsorbed atoms and carbon atom vacancies, with the help of density functional methods and correlated wavefunction techniques.

Recent works in the field comprise:

• Anomalous delocalization of resonant states in graphene & the vacancy magnetic moment
• Identification of Stable Configurations in the Superhydrogenation Sequence of Polycyclic Aromatic Hydrocarbon Molecules
• Dual-Route Hydrogenation of the Graphene/Ni Interface
• Sticking of hydrogen atoms on graphene
• Structure and stability of hydrogenated carbon atom vacancies in graphene
• Spin coupling around a carbon atom vacancy in graphene
• A few simple rules governing hydrogenation of graphene dots
• The effect of atomic–scale defects and dopants on graphene electronic structure
• Symmetry-induced band-gap opening in graphene superlattices
• Understanding adsorption of hydrogen atoms on graphene

Collaborations: L. Hornekaer, X. Tielens, R. Larciprete, S. Lizzit, M. I. Trioni

We investigate recombination reactions involving hydrogen atoms on graphitic substrates with the help of classical, ab–initio classical and quantum molecular dynamics methods, see e.g.

• Full quantum dynamical investigation of the Eley-Rideal reaction forming H₂ on a movable graphitic substrate at T = 0 K
• Classical and quantum dynamics at surfaces: Basic concepts from simple models
• Quantum dynamics of hydrogen atoms on graphene
• Insights into H₂ formation in space from ab initio molecular dynamics
• Surface models and reaction barrier in Eley–Rideal formation of H₂ on graphitic surfaces
• Quantum dynamics of Eley–Rideal hydrogen formation reaction on graphite at typical interstellar cloud conditions

Collaborations: D. Lemoine

We investigate charge and energy transport in the quantum regime, e.g. electron transport through nanojunctions and exciton dynamics in organic polymers, with the help of Green’s function based and time–dependent wavefunction methods. Some recent works are

• Magnetic Moments and Electron Transport through Chromium-Based Antiferromagnetic Nanojunctions
• Electron transport in carbon wires contacted to Ag electrodes: a detailed first principles investigation
• Hydrogen-dimer lines and electron waveguides in graphene
• Quantum dynamics of ultrafast charge transfer at a polymer–fullerene interface
• Coherent excitation transfer driven by torsional dynamics: a model Hamiltonian for PPV type systems

Collaborations: I. Burghardt, K.H. Hughes, M. I. Trioni, D. Ceresoli

We study the dynamics of small quantum systems coupled to an environemnt (modeling e.g. atoms on a surface) by applying brute-force multiconfiguration wavefunction techniques to recently developed effective mode representations of the bath.

Recent works comprise:

• Multi-configurational Ehrenfest simulations of ultrafast nonadiabatic dynamics in a charge-transfer complex
• Caldeira-Leggett model describes dynamics of hydrogen atoms on graphene
• Quantum dynamics of hydrogen atoms on graphene
• Vibrational relaxation and decoherence in structured environments: a numerical investigation
• Non-Markovian reduced dynamics of ultrafast charge transfer at an oligothiphene-fullerene heterojunction
• Quantum dynamics of ultrafast charge transfer at a polymer–fullerene interface
• Benchmark calculations for dissipative dynamics of a system coupled to an anharmonic bath with the multiconfiguration time–dependent Hartree method

Collaborations: I. Burghardt, K.H. Hughes

We address fundamental issues in theoretical chemistry.

Recent works comprise:

• Emergence of the Molecular Geometric Phase from Exact Electron–Nuclear Dynamics
• Dynamics of the molecular geometric phase
• Quantum Dynamics with Electronic Friction
• Local-In-Time Error in variational quantum dynamics
• The different story of π bonds
• Lower bounds for Coulombic systems
• Self-consistent theory of lower bounds for eigenvalues
• Lower bounds to eigenvalues of the Schroedinger equation by solution of a 90-y challenge
• To Bend or Not to Bend, the Dilemma of Multiple Bonds
• Unraveling a Brownian particle's memory with effective mode chains
• Universal Markovian reduction of Brownian particle dynamics

Collaborations: I. Burghardt, E. Pollak, K. H. Hughes, M. Cococcioni, D.M. Proserpio