High Level Electronic Structure Calculation of Molecular Solid-State NMR Shielding Constants

Abstract

In this work, we present a quantum mechanics/molecular mechanics (QM/MM) approach for the computation of solid-state nuclear magnetic resonance (SS-NMR) shielding constants (SCs) for molecular crystals. Besides applying standard-DFT functionals like GGAs (PBE), meta-GGAs (TPSS), and hybrids (B3LYP), we apply a double-hybrid (DSD-PBEP86) functional as well as MP2, using the domain-based local pair natural orbital (DLPNO) formalism, to calculate the NMR SCs of six amino acid crystals. All the electronic structure methods used exhibit good correlation of the NMR shieldings with respect to experimental chemical shifts for both 1 H and 13 C. We also find that local electronic structure is much more important than the long-range electrostatic effects for these systems, implying that cluster approaches using all-electron/Gaussian basis set methods might offer great potential for predictive computations of solid-state NMR parameters for organic solids.

Do Models beyond Hybrid Density Functionals Increase the Agreement with Experiment for Predicted NMR Chemical Shifts or Electric Field Gradient Tensors in Organic Solids?

“…They also found no meaningful chemical shift accuracy improvements from using MP2 or CCSD instead of PBE0, though they did observe the importance of spin–orbit and nuclear quantum effects, especially for protons in certain hydrogen bonding environments. Poidevin et al obtained generally similar results on the same set of amino acids with cluster models and double-hybrid functionals …”

“…Poidevin et al presented data on a small set of amino acids in which large cluster QM/MM calculations with double-hybrid functionals gave improved agreement with experiment compared to a monomer correction on top of GGA cluster results. 42 Accordingly, we performed a set of fragment-based chemical shift calculations with MP2 and PBE0-DH on the 15 N crystal test set. These fragment calculations can be viewed as an approximate finite-cluster treatment of the crystals; no GIPAW GGA calculations are involved.…”

“…Second, one might question if the monomer-correction approach itself is problematic. Poidevin et al presented data on a small set of amino acids in which large cluster QM/MM calculations with double-hybrid functionals gave improved agreement with experiment compared to a monomer correction on top of GGA cluster results . Accordingly, we performed a set of fragment-based chemical shift calculations with MP2 and PBE0-DH on the 15 N crystal test set.…”

“…Poidevin et al obtained generally similar results on the same set of amino acids with cluster models and double-hybrid functionals. 42 While these studies have all been very insightful, there has not yet been a broader study of the performance of MP2 or doublehybrid functionals for predicting experimental solid-state 13 C and 15 N chemical shifts in organic crystals. Nor has the performance of these models been investigated for other magnetic properties such as EFG tensor components.…”

Theoretical Study of Azetidine Derivative by Quantum Chemical Methods, Molecular Docking and Molecular Dynamic Simulations

“…The range of surface color is from−6.745e–2(red) to 6.745e–2(blue). Here, electrophilic red surfaces are mapped around oxygen atoms and nucleophilic blue surfaces are mapped around hydrogen atoms [48–50] …”