Real-time propagation of adaptive sampling selected configuration interaction wave function

TL;DR

This paper introduces TD-ASCI, a new real-time propagation method for strongly correlated systems, utilizing the SIL integrator and efficient Fourier transform techniques to evaluate molecular absorption spectra.

Contribution

The paper presents the development of TD-ASCI, a novel time-dependent adaptive sampling CI method, combined with a stable SIL integrator and advanced FT scheme for efficient spectral analysis.

Findings

TD-ASCI accurately reproduces absorption spectra of molecular systems.

The method is computationally efficient due to the ESPRIT-based FT scheme.

Results compare favorably with EOMCC spectra for strongly correlated molecules.

Abstract

We have developed a new time propagation method, time-dependent adaptive sampling configuration interaction (TD-ASCI), to describe the dynamics of a strongly correlated system. We employ the short iterative Lanczos (SIL) method as the time-integrator, which provides a unitary, norm-conserving, and stable long-time propagation scheme. We used the TD-ASCI method to evaluate the time-domain correlation functions of molecular systems. The accuracy of the correlation function was assessed by Fourier transforming (FT) into the frequency domain to compute the dipole-allowed absorption spectra. The FT has been carried out with a short-time signal of the correlation function to reduce the computation time, using an efficient alternative FT scheme based on the ESPRIT signal processing algorithm. We have applied the {TD-ASCI} method to prototypical strongly correlated molecular systems and compared the absorption spectra to spectra evaluated using the equation of motion coupled cluster (EOMCC) method with a truncation at single-doubles-triples (SDT) level.