Polarizable embedding complex polarization propagator in four- and two-component frameworks

TL;DR

This paper introduces the first implementation of the complex polarization propagator within four- and two-component polarizable embedding frameworks, enabling accurate modeling of solvent effects on spectroscopy of complex systems.

Contribution

The paper develops and implements PE-4c-CPP and PE-X2C-CPP methods, extending complex polarization propagator techniques to advanced embedding frameworks for the first time.

Findings

Solvent effects significantly alter UV-vis and XAS spectra compared to vacuum calculations.

X2C reproduces solvent effects with high accuracy, matching four-component results.

Including environment effects is crucial for realistic spectral modeling.

Abstract

Explicit embedding methods combined with the complex polarization propagator (CPP) enable modeling of spectroscopy for increasingly complex systems with a high density of states. We present the first derivation and implementation of the CPP in four- and exact two-component (X2C) polarizable embedding (PE) frameworks. We denote the developed methods PE-4c-CPP and PE-X2C-CPP, respectively. We illustrate the methods by estimating the solvent effect on UV-vis and X-ray atomic absorption (XAS) spectra of [Rh(H2O)6]3+ and [Ir(H2O)6]3+ immersed in aqueous solution. We moreover estimate solvent effects on UV-vis spectra of a platinum complex that can be photo-chemically activated (in water) to kill cancer cells. Our results clearly show that inclusion of the environment is required: UV-vis and (to a lesser degree) XAS spectra can become qualitatively different from vacuum calculations. Comparison of PE-4c-CPP and PE-X2C-CPP methods shows that X2C essentially reproduces the solvent effect obtained with the 4c methods.