QTPIE: Charge Transfer with Polarization Current Equalization. A fluctuating charge model with correct asymptotics

TL;DR

QTPIE is a novel charge transfer model that accurately describes polarization and charge transfer effects, especially near bond dissociation, improving reactive molecular simulations.

Contribution

The paper introduces QTPIE, a charge transfer model based on transfer variables, with correct asymptotics and improved polarization description, addressing limitations of previous models.

Findings

Correct asymptotic behavior near dissociation

Realistic in-plane polarizabilities

Applicable to reactive force fields

Abstract

Polarization and charge transfer are important effects which are difficult to describe using conventional force fields. Charge equilibration models can include both of these effects in large-scale molecular simulations. However, these models behave incorrectly when bonds are broken, making it difficult to use them in the context of reactive force fields. We develop a new method for describing charge flow in molecules -- QTPIE. The QTPIE method is based on charge transfer variables (as opposed to atomic charges) and correctly treats asymptotic behavior near dissociation. It is also able to provide a realistic description of in-plane polarizabilities.