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arXiv · 1608.04266

Separation of Dynamic and Nondynamic Correlation

Eloy Ramos-Cordoba·Pedro Salvador·Eduard Matito
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Abstract

The account of electron correlation and its efficient separation into dynamic and nondynamic parts plays a key role in the development of computational methods. In this paper we suggest a physically-sound matrix formulation to split electron correlation into dynamic and nondynamic parts using the two-particle cumulant matrix and a measure of the deviation from idempotency of the first-order density matrix. These matrices are applied to a two-electron model, giving rise to a simplified electron correlation index that ($i$) depends only on natural orbitals and their occupancies, ($ii$) can be straightforwardly decomposed into orbital contributions and ($iii$) splits into dynamic and nondynamic correlation parts that ($iv$) admit a local version. These expressions are shown to account for dynamic and nondynamic correlation in a variety of systems containing different electron correlation regimes, thus providing the first separation of dynamic and nondynamic correlation using solely natural orbital occupancies.

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Eloy Ramos-Cordoba, Pedro Salvador, Eduard Matito. 2016-08-15. Separation of Dynamic and Nondynamic Correlation. https://doi.org/10.1039/c6cp03072f

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