Dielectric properties of condensed systems composed of fragments

TL;DR

This paper introduces a first-principles method to accurately compute the dielectric polarizabilities of molecules and nanostructures within condensed phases, accounting for multipolar interactions at all orders, applicable to various materials.

Contribution

It presents a novel, efficient approach for calculating polarizabilities in solids and liquids without multiple separate calculations for each component.

Findings

At ambient conditions, the dipole-induced-dipole approximation is sufficient.

The Clausius-Mossotti relation can be used to derive polarizabilities from refractive indexes.

Under high pressure, the approximation and relation become unreliable, especially for ice X.

Abstract

The dielectric properties of molecules or nanostructures are usually modified in a complex manner, when assembled into a condensed phase. We propose a first-principles method to compute polarizabilities of sub-entities of solids and liquids, which accounts for multipolar interactions at all orders, and is applicable to any semiconductor or insulator. The method only requires the evaluation of induced fields in the condensed phase, with no need of multiple calculations for each constituent. As an example, we present results for the molecular polarizabilities of water in a wide pressure and temperature range. We found that at ambient conditions, the dipole-induced-dipole approximation is sufficiently accurate and the Clausius-Mossotti relation may be used, e.g. to obtain molecular polarizabilities from experimental refractive indexes. However with increasing pressure this approximation becomes unreliable and in the case of ice X the Clausius-Mossotti relation is not valid.