0000000000338007
AUTHOR
Evert Jan Baerends
Oscillator Strengths of Electronic Excitations with Response Theory using Phase Including Natural Orbital Functionals
The key characteristics of electronic excitations of many-electron systems, the excitation energies ωα and the oscillator strengths fα, can be obtained from linear response theory. In one-electron models and within the adiabatic approximation, the zeros of the inverse response matrix, which occur at the excitation energies, can be obtained from a simple diagonalization. Particular cases are the eigenvalue equations of time-dependent density functional theory (TDDFT), time-dependent density matrix functional theory, and the recently developed phase-including natural orbital (PINO) functional theory. In this paper, an expression for the oscillator strengths fα of the electronic excitations is…
Time-Dependent Reduced Density Matrix Functional Theory
In this chapter we will give an introduction into one-body reduced density matrix functional theory (RDMFT). This is a rather new method to deal with the quantum many-body problem. Especially the development of a time-dependent version, TDRDMFT , is very recent. Therefore, there are many open questions and the formalism has not crystalized yet into a standard form such as in (TD)DFT. Although RDMFT has similarities with DFT, there are many more differences. This chapter is too short for a full introduction into the wondrous world of RDMFT, but we hope to give an idea what (TD)RDMFT might bring.
Response calculations based on an independent particle system with the exact one-particle density matrix: Excitation energies
Adiabatic response time-dependent density functional theory (TDDFT) suffers from the restriction to basically an occupied → virtual single excitation formulation. Adiabatic time-dependent density matrix functional theory allows to break away from this restriction. Problematic excitations for TDDFT, viz. bonding-antibonding, double, charge transfer, and higher excitations, are calculated along the bond-dissociation coordinate of the prototype molecules H2 and HeH+ using the recently developed adiabatic linear response phase-including (PI) natural orbital theory (PINO). The possibility to systematically increase the scope of the calculation from excitations out of (strongly) occupied into wea…