Natural bond orbital‐based energy density analysis for correlated methods: Second‐order Møller–Plesset perturbation and coupled‐cluster singles and doubles

Abstract

Natural bond orbital-based energy density analysis (NBO-EDA), which split energies into atomic and bonding contributions, is proposed for correlated methods such as coupled-cluster singles and doubles (CCSD) and second-order Møller-Plesset (MP2) perturbation. Applying NBO-EDA for CCSD and MP2 to ethylene and the Diels-Alder reaction, we are successful in obtaining useful knowledge regarding electron correlation of -and -type orbitals, and clarifying the difference of the reaction barriers and heat of reaction calculated by CCSD and MP2.

Theory and practice of modeling van der Waals interactions in electronic-structure calculations

“…95,107 This already hints at a very important point: In order to obtain the contribution of vdW interactions, the underlying method used for the constrained SCF procedure must explicitly account for dispersion forces and desirably, higher-order terms too. Because of this, many schemes have been re-expressed at higher levels of theory, such as coupled cluster [108][109][110] or dispersion-corrected DFT. [111][112][113] As of today, a vast number of methodologies and flavors of variational energy decomposition techniques has been devised and above we only presented a few, select examples.…”

Kinetic energy decomposition scheme based on information theory

“…The three partitionings using transformed orbitals, space‐partitioning functions, and atomic regions determined by the Theory of Atoms‐in‐Molecules, have been also adopted as an energy decomposition scheme. The representative analysis for the first type of partitioning is natural population analysis .…”

A resonance theory consistent with Mulliken-population concept

“…Another type of analysis based on locally defined energy by Nakai et al can also offer detailed inside of the electronic structure of a molecule and its bonds. [15][16][17][18][19][20][21][22][23][24] Several types of analysis methods have been traditionally developed. Mulliken population analysis (MPA) and ab-initio bond order analysis (BOA) are the representative.…”