The effect of uncertainty on building blocks in molecules

TL;DR

This paper explores how uncertainty influences the probabilities of electron arrangements in molecules, highlighting the importance of flexible definitions and alternative distributions for understanding chemical bonding.

Contribution

It introduces a flexible framework for analyzing electron distributions and proposes a new tool, the effective number of parties, to aid in selecting relevant reference states.

Findings

Quantum mechanics can yield higher probabilities for chemically relevant electron arrangements.

The probability of specific electron arrangements is generally low but often maximal for certain configurations.

A new conceptual tool, the effective number of parties, is proposed to assist in analyzing electron distributions.

Abstract

Probabilities to find a chosen number of electrons in flexible domains of space are calculated for highly correlated wave functions. Quantum mechanics can produce higher probabilities for chemically relevant arrangements of electrons in these regions. However, the probability to have a given arrangement, e.g., that corresponding to chemical formulas (bonds or atoms), is low although being often maximal. Like in valence bond theory, it is useful to consider alternative distributions of the electrons. Exchanges of electrons should be considered not only between atoms, but also between other types of regions, like those attributed to lone pairs. It is useful to have definitions flexible enough to allow the user to find the reference representations he considers most relevant. We tentatively suggest a tool (the effective number of parties) to help one make the choice.