Abstract
A new valence bond (VB)-based multireference density functional theory (MRDFT) method, named λ-DFVB, is presented in this paper. The method follows the idea of the hybrid multireference density functional method theory proposed by Sharkas et al. (2012). λ-DFVB combines the valence bond self-consistent field (VBSCF) method with Kohn–Sham density functional theory (KS-DFT) by decomposing the electron–electron interactions with a hybrid parameter λ. Different from the Toulouse's scheme, the hybrid parameter λ in λ-DFVB is variable, defined as a function of a multireference character of a molecular system. Furthermore, the EC correlation energy of a leading determinant is introduced to ensure size consistency at the dissociation limit. Satisfactory results of test calculations, including potential energy surfaces, bond dissociation energies, reaction barriers, and singlet–triplet energy gaps, show the potential capability of λ-DFVB for molecular systems with strong correlation.
Highlights
One of the major interests in quantum chemistry is the methodology development for electronic correlation energy calculation with an affordable computational cost
A new hybrid multireference density functional theory method based on the valence bond (VB) theory, named λ-DFVB, is presented in this paper
Based on the MC1H approximation presented by Sharkas et al (2012), λ-DFVB combines valence bond self-consistent field (VBSCF) and Kohn–Sham density functional theory (KS-DFT) with a linear decomposition for electron–electron interactions
Summary
One of the major interests in quantum chemistry is the methodology development for electronic correlation energy calculation with an affordable computational cost. Two valence bond wave function-based MRDFT (DFVB) methods are presented: the first one is the dynamic correlation-corrected density functional valence bond (dc-DFVB) method (Ying et al, 2012), and the second one is the Hamiltonian matrix correction-based density functional valence bond (hc-DFVB) method (Zhou et al, 2017) These two methods are capable of providing satisfactory accuracy with relatively cheaper computational costs, compared to the currently existing post-VBSCF methods. These two methods still suffer from double counting error (DCE)
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