Design of effective kernels for spectroscopy and molecular transport: time-dependent current-density-functional theory

TL;DR

This paper develops a new approach combining time-dependent current-density-functional theory with many-body perturbation theory to improve the calculation of response functions in complex systems, enabling more accurate and efficient spectral and conductance predictions.

Contribution

It derives an exact equation for the exchange-correlation kernel in TDCDFT and proposes an approximate kernel for practical spectral and conductance calculations.

Findings

Derived an exact exchange-correlation kernel equation for TDCDFT.

Proposed an approximate kernel for spectra of solids and molecular conductances.

Discussed the validity of the approximate kernel in practical applications.

Abstract

Time-dependent current-density-functional theory (TDCDFT) provides an in principle exact scheme to calculate efficiently response functions for a very broad range of applications. However, the lack of approximations valid for a range of parameters met in experimental conditions has so far delayed its extensive use in inhomogeneous systems. On the other side, in many-body perturbation theory (MBPT) accurate approximations are available, but at a price of a higher computational cost. In the present work the possibility of combining the advantages of both approaches is exploited. In this way an exact equation for the exchange-correlation kernel of TDCDFT is obtained, which opens the way for a systematic improvement of the approximations adopted in practical applications. Finally, an approximate kernel for an efficient calculation of spectra of solids and molecular conductances is suggested and its validity discussed.