Second-Generation Energy Decomposition Analysis of Intermolecular Interaction Energies from the Second-Order Mo̷ller–Plesset Theory: An Extensible, Orthogonal Formulation with Useful Basis Set Convergence for All Terms

Journal of Chemical Theory and Computation, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 21, 2025

Energy decomposition analysis (EDA) based on density functional theory (DFT) and self-consistent field (SCF) calculations has become widely used for understanding intermolecular interactions. This work reports a new approach to EDA post-SCF wave functions closed-shell restricted second-order Mo̷ller-Plesset (MP2) together with an efficient implementation that generalizes the successful SCF-level second-generation absolutely localized molecular orbital approach, ALMO-EDA-II, improves upon MP2 ALMO-EDA-I. The ALMO-EDA-II provides distinct energy contributions frozen interaction containing permanent electrostatics Pauli repulsions, polarized energy-yielding induced electrostatics, dispersion-corrected energy, fully relaxed which describes charge transfer. All terms have useful complete basis set limits due design of theory, corroborated by range test model systems, S22 Ionic43 data sets weak strong interactions, respectively. Comparisons DFT-based suggest yields quite consistent interpretation interactions when total energies are consistent. To begin address limitations itself, was also implemented κ-regularized size-consistent Brillouin-Wigner (BW-s2) method, both more accurate dispersion-dominated principal limitation is associated need obtain orthogonal fragment-localized virtual orbitals, leads clearly poorer results using atomic contain diffuse functions. We therefore recommend nonaugmented sets.

Language: Английский

The conundrum of diffuse basis sets: A blessing for accuracy yet a curse for sparsity

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(18)

Published: May 9, 2025

Diffuse atomic orbital basis sets have proven to be essential obtain accurate interaction energies, especially in regard non-covalent interactions. However, they also a detrimental impact on the sparsity of one-particle density matrix (1-PDM), degree stronger than spatial extent functions alone could explain. This is despite fact that elements 1-PDM insulators (systems with significant highest occupied molecular orbital–lowest unoccupied gaps) are expected decay exponentially increasing real-space distance from diagonal. The observed low appears independent representation and even persists after projecting onto grid, leading conclusion this “curse sparsity” solely set artifact, which, counterintuitively, becomes worse for larger sets, seemingly contradicting notion well-defined limit. We show consequence locality contra-variant as quantified by inverse overlap S−1 being significantly less sparse its co-variant dual. Introducing model system an infinite non-interacting chain helium atoms, we able quantify exponential rate proportional diffuseness well local incompleteness set, meaning small diffuse affected most. Finally, propose one solution conundrum form complementary auxiliary singles correction combination compact, l-quantum-number showing promising results

Language: Английский