The nuclear electronic orbital (NEO) approach includes non-adiabatic and nuclear quantum effects for select nuclei by treating these nuclei quantum mechanically in a manner consistent to the electrons. Due to the attractive interaction of electrons and protons and the lack of electron-proton correlation, mean-field based NEO approaches give a much too localized nuclear density when compared to benchmark grid-based approaches. NEO approaches that include explicit electron-proton correlation give an accurate nuclear density along a single-dimension of a molecule, but require the computation of up to five particle integrals, severely limiting applicability. Additionally, explicitly correlated NEO approaches have difficulty computing accurate nuclear densities in all dimensions for adiabatic systems due to limitations of the explicitly correlated NEO ansatz. Because of these difficulties, recent NEO research has focused on the development of multicomponent (MC) density functional theory (DFT) functionals. One recently developed functional, based on the Colle-Salvetti formulation of the correlation energy, has shown the ability to reproduce the density of grid-based approaches, while having similar computational scaling to that of standard electronic DFT. This MC-DFT approach allows for the inclusion of nuclear quantum effects for a wide variety of chemical applications. A brief overview of wavefunction and DFT based NEO approaches, the ability of these approaches to compute nuclear densities, and initial chemical applications of the Colle-Salvetti based NEO-DFT functional will be presented.

Computing nuclear quantum effects with the nuclear electronic orbital approach

254th National Meeting (2017)

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