St. Albert Hall B-37
Department of Physics, St. John’s
University Society of Physics Students Chapter
Time Dependent Density
A study on development and
Dr. Arun Rajam, Department of
Physics, St. John’s University, Jamaica, NY
Time dependent density functional theory (TDDFT) is one of the
useful tools for the study of the dynamic behavior of correlated
electronic systems under the influence of external potentials.
The success of this formally exact theory practically relies on
approximations for the exchange-correlation potential which is a
complicated non-local functional of the co-ordinate density.
Adiabatic local approximations have been proposed and employed in
several pioneering works of this field . However these
approximations were found to suffer from mathematical
inconsistencies and general applicability demands especially in the
regime of strong field dynamics.
We explore the regions where the theory faces challenges, and
try to answer some of them via the insights from the many electron
model systems. We want to answer the challenges the theory is
facing currently by exploring the phase-space and semi-classical
methods. The evolution scheme of the 1RDM (first order reduced
density matrix) contains second-order reduced density matrix
(2RDM), which has to be truncated in terms of 1RDMs. Any
non-correlated approximations (Hartree-Fock) for 2RDM would fail to
capture the natural occupations of the system. We show that by
applying the quasi-classical and semi-classical approximations one
can capture the natural occupations of the excited systems.