Quantum Monte Carlo study of three-dimensional Coulomb complexes: trions and biexcitons; hydrogen molecules and ions; helium hydride cations; and positronic and muonic complexes

TL;DR

This paper uses diffusion quantum Monte Carlo methods to accurately study the binding energies and properties of various three- and four-body Coulomb complexes, including excitons, molecules, and ions, in different environments.

Contribution

It provides statistically exact calculations and interpolation formulas for binding energies of Coulomb complexes in bulk and free space, incorporating vibrational effects.

Findings

Accurate binding energies for trions and biexcitons in 3D semiconductors.

Interpolation formulas for predicting complex energies.

Insights into vibrational effects in small molecules.

Abstract

Three-dimensional (3D) excitonic complexes influence the optoelectronic properties of bulk semiconductors. More generally, correlated few-particle molecules and ions, held together by pairwise Coulomb potentials, play a fundamental role in a variety of fields in physics and chemistry. Based on statistically exact diffusion quantum Monte Carlo calculations, we have studied excitonic three- and four-body complexes (trions and biexcitons) in bulk 3D semiconductors as well as a range of small molecules and ions in which the nuclei are treated as quantum particles on an equal footing with the electrons. We present interpolation formulas that predict the binding energies of these complexes either in bulk semiconductors or in free space. By evaluating pair distribution functions within quantum Monte Carlo simulations, we examine the importance of harmonic and anharmonic vibrational effects in small molecules.