Assessing the domain-based local pair natural orbital (DLPNO) approximation for non-covalent interactions in sizable supramolecular complexes DOI Creative Commons
Montgomery Gray, John M. Herbert

Published: March 4, 2024

The titular DLPNO approximation has become a de facto standard for extending correlated wave function models to large molecular systems yet its fidelity intermolecular interaction energies not been thoroughly vetted. Non-covalent are sensitive tails of the electron density, involving parts that far from nuclei and may be discarded in some local correlation treatments. Meanwhile, accuracy is known deteriorate as size increases questions have raised regarding benchmark calculations van der Waals complexes. Here, we test at level second-order Moller-Plesset perturbation theory (MP2) with up 240 atoms, which canonical MP2 can performed comparison. For small dimers, find DLPNO-MP2 within 3% values but quite poor larger systems, unless results extrapolated limit where threshold discarding PNOs taken zero. sequence nanoscale graphene dimers (C96H24)2, agree 1%, independent system size, provided basis set does contain diffuse functions. presence functions causes oscillatory behavior PNO threshold, making it impossible extrapolate meaningful way.

Language: Английский

Density functional theory for van der Waals complexes: Size matters DOI Creative Commons
Montgomery Gray, John M. Herbert

Published: Feb. 7, 2024

Over the past 25 years there has been remarkable progress towards accurate description of nonbonded interactions within context density functional theory (DFT). Various methods have devised to capture London dispersion, which is most exacting contribution noncovalent interactions; these strategies include both new functionals as well ad hoc dispersion corrections existing functionals. At present, it possible compute interaction energies for small van der Waals complexes (containing ~20 atoms) an accuracy ~0.5 kcal/mol, using a range dispersion-inclusive DFT that are reviewed here. Systematic tests reveal consistency across different methods, at least dimers. same time, magnitude systematically smaller than benchmark because some resides semilocal exchange-correlation functional, in manner difficult disentangle. Despite impressive results systems, best contemporary afford larger errors systems with >~ 100 atoms, approaching 3-5 kcal/mol compared ab initio benchmarks total energies, although themselves uncertainties this size. Errors vary widely from one method next, no discernible systematic trend. Nanoscale thus represent frontier development interactions.

Language: Английский

Citations

4
Advancing Non-Atom-Centered Basis Methods for More Accurate Interaction Energies: Benchmarks and Large-Scale Applications DOI Creative Commons
Balázs D. Lőrincz, Péter R. Nagy

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 18, 2024

Recent advances in local electron correlation approaches have enabled the relatively routine access to CCSD(T) [that is, coupled cluster (CC) with single, double, and perturbative triple excitations] computations for molecules of a hundred or more atoms. Here, approaching their complete basis set (CBS) limit becomes challenging due extensive superposition errors, often necessitating use large atomic orbital (AO) sets diffuse functions. we study potential remedy form non-atom-centered floating orbitals (FOs). FOs are still rarely employed even small practical complication defining position, number, exponents, etc. The most frequently used FO method thus simply places single center number toward middle noncovalent dimers; however, larger complexes can soon become insufficient. A recent alternative uses grid centers around monomers s function per center, which is currently applicable only H, C, N, O build on above advantages mitigate some drawbacks previous by using layer 4-9 FOs/center each monomer. Thus, double placed between interacting subsystems. When extending double-ζ AO this FOs, quality conventional augmented triple-ζ bases be reached surpassed less orbitals, leading few tenths kcal/mol errors medium-sized dimers. This good performance extends (shown here up 72 atoms), as efficient natural (LNO) 4 match our LNO-CCSD(T)/CBS reference within ca. 0.1 kcal/mol. These developments introduce methods accurate modeling molecular without limitations atom types further accelerating calculations, like LNO-CCSD(T).

Language: Английский

Citations

2
Eliminating imaginary vibrational frequencies in quantum-chemical cluster models of enzymatic active sites DOI Creative Commons
Paige E. Bowling, Saswata Dasgupta, John M. Herbert

et al.

Published: Feb. 9, 2024

In constructing finite models of enzyme active sites for use in quantum-chemical calculations, atoms at the periphery model system are often constrained to prevent structural collapse during geometry relaxation. A simple fixed-atom or ``coordinate lock'' approach is commonly employed but leads undesirable artifacts including appearance small imaginary frequencies. These preclude evaluation finite-temperature free energy corrections, limiting thermochemical calculations enthalpies only. Full-dimensional vibrational frequency possible by replacing constraints with harmonic confining potentials, and here we compare that an alternative strategy which contributions Hessian simply omitted. While does eliminate frequencies, it tends underestimate both zero-point entropy, addition artificial rigidity already introduced constraints. Harmonic potentials frequencies provide a flexible means construct can be used unconstrained relaxations.

Language: Английский

Citations

1
Assessing the domain-based local pair natural orbital (DLPNO) approximation for non-covalent interactions in sizable supramolecular complexes DOI Creative Commons
Montgomery Gray, John M. Herbert

Published: March 4, 2024

The titular DLPNO approximation has become a de facto standard for extending correlated wave function models to large molecular systems yet its fidelity intermolecular interaction energies not been thoroughly vetted. Non-covalent are sensitive tails of the electron density, involving parts that far from nuclei and may be discarded in some local correlation treatments. Meanwhile, accuracy is known deteriorate as size increases questions have raised regarding benchmark calculations van der Waals complexes. Here, we test at level second-order Moller-Plesset perturbation theory (MP2) with up 240 atoms, which canonical MP2 can performed comparison. For small dimers, find DLPNO-MP2 within 3% values but quite poor larger systems, unless results extrapolated limit where threshold discarding PNOs taken zero. sequence nanoscale graphene dimers (C96H24)2, agree 1%, independent system size, provided basis set does contain diffuse functions. presence functions causes oscillatory behavior PNO threshold, making it impossible extrapolate meaningful way.

Language: Английский

Citations

1