"Embedding Ground and Excited States in Real and Imaginary Time"
Fall 2016 Colloquium Series
|Speaker: Professor Michele Pavanello
Department of Chemistry
Rutgers University, Newark
Abstract: Over the past four years the Pavanello Research Group has developed an array of density embedding methods for the description of periodic and molecular systems alike, their Born-Oppenheimer adiabatic dynamics, as well as excited states dynamics. The overarching goal of this effort has been to allow first principle simulations to approach realistic time- and length-scales, and to shed light on the dynamical behavior of complex systems. Our theory development has resulted in a new open-source density embedding software called embedded Quantum-ESPRESSO – eqe.rutgers.edu.
When inspecting the electron dynamics between molecular subsystems in real time, we observe all the relevant regimes proper of non-Markovian open system dynamics, such as charge and electronic energy transfer, superexchange, and screening. When propagating the dynamics in imaginary time, we gain access to the dissipative van der Waals interactions between subsystems.
In this talk we present electron and nuclear dynamics simulations of liquid water on a model system containing up to 256 independent water molecules, revealing correlations between nuclear dynamics and optical spectra of the liquid. We also present model electronic spectra of triplet excitons in crystalline tetracene and pentacene. The density embedding treatment allows us to quantify cooperative excitonic effects in these systems.
By carrying out the dynamics in imaginary time, we compare our computed interaction energies with the S22 and S22-5 benchmark sets. Due to the theoretically exact framework, we are able to provide clear prescriptions for improving van der Waals parameters of current force fields which are based on the Random Phase Approximation.
|Host: Professor Lu Wang|
|~ Coffee/tea will be served prior to lecture ~|