Intermolecular Interactions in Static Electric Fields Studied with Quantum Mechanics and Quantum Electrodynamics
In this work, the interactions between neutral molecular systems subject to external static electric fields are studied. To this end, the two most reliable frameworks in the subject, namely molecular quantum mechanics and quantum electrodynamics are employed while atomic and molecular responses are modeled using quantum Drude oscillators (QDO). In the first part of the work, the focus is to understand the interplay between dispersion and field-induced forces in two-body systems for both nonretarded and retarded ranges of intermolecular distances. To identify the origin and the mechanism responsible for different field-induced interactions, a complementary approach based on classical electrodynamics with a zero-point radiation field, namely stochastic electrodynamics, is employed. The results show that neglecting higher-order contributions coming from field-induced hyperpolarizabilities of atoms, the dispersion interaction remains unchanged by the external uniform static field, for both regimes. However, using an external static field one can control the magnitude and characteristics of intermolecular interactions. The second part of the work is devoted to the extension of the study to many-body (atoms/molecules) interacting systems. The impact of the field-induced many-body contributions is investigated for a benzene dimer as well as for two carbyne chains where the results show a strong deviation of the field-induced interactions from pairwise additivity. Varying the number of carbon atoms per chain demonstrates the significance of the field-induced many-body terms in the interplay between dispersion and field-induced interactions. Such contributions can be of great importance for controlling delamination and self-assembly of materials in static electric fields.
Dissertation defence jury
Chair: Prof. Dr. Thomas Schmidt, Université du Luxembourg
Vice-Chair: Prof. Dr. Massimiliano Esposito, Université du Luxembourg
Supervisor (Member): Prof. Dr. Alexandre Tkatchenko, Université du Luxembourg
Member: Prof. Katharine Clarke Hunt, Michigan State University
Member: Dr. Johannes Flick, Center for Computational Quantum Physics, Flatiron Institute, New York