# Local descriptors of dynamic and nondynamic correlation

## TL;DR

This paper introduces real-space local descriptors for dynamic and nondynamic electron correlation, enabling orbital decomposition and quantification of correlation effects in various chemical systems.

## Contribution

It presents novel local descriptors that distinguish dynamic and nondynamic correlation regions, applicable in multiple quantum chemistry methods.

## Key findings

- Descriptors successfully differentiate correlation types in diverse systems
- Global correlation measures correlate with chemical properties
- Method integrates easily with existing computational frameworks

## Abstract

Quantitatively accurate electronic structure calculations rely on the proper description of electron correlation. A judicious choice of the approximate quantum chemistry method depends upon the importance of dynamic and nondynamic correlation, which is usually assessed by scalar measures. Existing measures of electron correlation do not consider separately the regions of the Cartesian space where dynamic or nondynamic correlation are most important. We introduce real-space descriptors of dynamic and nondynamic electron correlation that admit orbital decomposition. Integration of the local descriptors yields global numbers that can be used to quantify dynamic and nondynamic correlation. Illustrative examples over different chemical systems with varying electron correlation regimes are used to demonstrate the capabilities of the local descriptors. Since the expressions only require orbitals and occupation numbers, they can be readily applied in the context of local correlation methods, hybrid methods, density matrix functional theory and fractional-occupancy density functional theory.