Jeremie Messud

Time-dependent density-functional theory with a self-interaction correction.

We discuss an implementation of the self-interaction correction for the local-density approximation to time-dependent density-functional theory. A variational formulation is given, taking care of the necessary constraints. A manageable and transparent propagation scheme using two sets of wave functions is proposed and applied to laser excitation with subsequent ionization of a dimer molecule.

On the exact treatment of time-dependent self-interaction correction

We present a new formulation of the time-dependent self-interaction correction (TDSIC). It is derived variationally obeying explicitly the constraints on orthonormality of the occupied single-particle orbitals. The thus emerging rather involved symmetry condition amongst the orbitals is dealt with using two separate sets of (occupied) single-particle wavefunctions, related by a unitary transformation. The double-set TDSIC scheme is well suited for numerical implementation. We present results for laser-excited dynamics in a 1D model for a molecule and in fully fledged 3D calculations.

The Generalized SIC-OEP formalism and the Generalized SIC-Slater approximation (stationary and time-dependent cases).

We present a generalized formulation of the Optimized Effective Potential (OEP) approach to the Self Interaction Correction (SIC) problem in Time Dependent (TD) Density Functional Theory (DFT). The formulation relies on the introduction of a double set of single electron orbitals. It allows the derivation of a generalized Slater approximation to the full OEP formulation, which extends the domain of validity of the standard Slater approximation. We discuss both formal aspects and practical applications of the new formalism and give illustrations in cluster and molecules. The new formalism provides a valuable ansatz to more elaborate (and computationally very demanding) full TD OEP and full TD SIC calculations especially in the linear domain.

The self-interaction correction in the time domain

We provide a brief outline of the Self Interaction Correction (SIC) used in connection with the Local Density Approximation (LDA) of Density Functional Theory (DFT), pointing out especially the implications for Time Dependent theories (TDDFT). We discuss how the self-interaction problem can be resolved by a clean formulation of the SIC theory including in an explicit manner the ortho-normalization of Kohn Sham orbitals. We finally show a few examples of applications of the theory.

Self-interaction correction in a simple model

We discuss various ways to handle self-interaction corrections (SIC) to Density Functional Theory (DFT) calculations. To that end, we use a simple model of few particles in a finite number of states together with a simple zero-range interaction for which full Hartree-Fock can easily be computed as a benchmark. The model allows to shed some light on the balance between orthonormality of the involved states and energy variance.

Time-dependent internal density functional theory formalism and Kohn-Sham scheme for self-bound systems

We generalize to the time-dependent case the stationary Internal DFT / Kohn-Sham formalism presented in Ref. [14]. We prove that, in the time-dependent case, the internal properties of a self-bound system (as an atomic nuclei or a Helium droplet) are all defined by the internal one-body density and the initial state. We set-up a time-dependent Internal Kohn-Sham scheme as a practical way to compute the internal density. The main difference with the traditional DFT / Kohn-Sham formalism is the inclusion of the center-of-mass correlations in the functional.

Dynamical hierarchical method for the irradiation of clusters and molecules in an environment

We present a short progress report of the microscopic theoretical description of the irradiation dynamics of small molecules. We discuss separately the short time response of the system to an electromagnetic perturbation and the impact of the environment on irradiation dynamics in the case of embedded metal clusters. We finally discuss some formal theoretical questions raised by the use of density functional theory in this context.

Electron emission to analyze cluster dynamics

We present a brief review of typical theoretical methods used to analyze cluster dynamics on the basis of electronic emission. After putting the various possible theories in perspective, we focus on a few examples of application, concerning in particular photoelectron spectroscopy and photoelectron angular distributions. We finally conclude by considering the case of high laser frequencies as delivered by free electron lasers and investigate the impact of such frequencies on cluster ionization.

ON TIME DEPENDENT DFT WITH SIC

We discuss an extension of time dependent density functional theory by a self-interaction correction (SIC). A strictly variational formulation is given taking care of the necessary constraints. A manageable and transparent propagation scheme using two sets of wave-functions is proposed and applied to laser excitation with subsequent ionization of a dimer molecule.